Maternal carbohydrate intake and pregnancy outcome

Maternal Dietary Carbohydrate and Pregnancy Outcomes: Quality over Quantity

Dietary nutrition plays a crucial role in determining pregnancy outcomes, with poor diet being a major contributor to pregnancy metabolic syndrome and metabolic disorders in offspring. While carbohydrates are essential for fetal development, the excessive consumption of low-quality carbohydrates can increase the risk of pregnancy complications and have lasting negative effects on offspring development. Recent studies not only highlighted the link between carbohydrate intake during pregnancy, maternal health, and offspring well-being, but also suggested that the quality of carbohydrate foods consumed is more critical. This article reviews the impacts of low-carbohydrate and high-carbohydrate diets on pregnancy complications and offspring health, introduces the varied physiological effects of different types of carbohydrate consumption during pregnancy, and emphasizes the importance of both the quantity and quality of carbohydrates in nutritional interventions during pregnancy. These findings may offer valuable insights for guiding dietary interventions during pregnancy and shaping the future development of carbohydrate-rich foods.

Carbohydrate-Mediated Pregnancy Gut Microbiota and Neonatal Low Birth Weight

The effects of gut microbiota on the association between carbohydrate intake during pregnancy and neonatal low birth weight (LBW) were investigated. A prospective cohort study was conducted with 257 singleton-born mother-child pairs in Taiwan, and maternal dietary intake was estimated using a questionnaire, with each macronutrient being classified as low, medium, or high. Maternal fecal samples were collected between 24 and 28 weeks of gestation, and gut microbiota composition and diversity were profiled using 16S rRNA amplicon gene sequencing. Carbohydrates were the major source of total energy (56.61%), followed by fat (27.92%) and protein (15.46%). The rate of infant LBW was 7.8%, which was positively correlated with maternal carbohydrate intake. In the pregnancy gut microbiota, Bacteroides ovatus and Dorea spp. were indirectly and directly negatively associated with fetal growth, respectively; Rosenburia faecis was directly positively associated with neonatal birth weight. Maternal hypertension during pregnancy altered the microbiota features and was associated with poor fetal growth. Microbiota-accessible carbohydrates can modify the composition and function of the pregnancy gut microbiota, thus providing a potential marker to modulate deviations from dietary patterns, particularly in women at risk of hypertension during pregnancy, to prevent neonatal LBW.

Maternal macronutrient and energy intake during pregnancy: a systematic review and meta-analysis

BACKGROUND

Nutritional status during pregnancy can have a significant impact on infant and maternal health outcomes. To maintain maternal homeostasis and support fetal growth, adequate macronutrient and energy intake during pregnancy is essential. Therefore, this study sought to systematically review and meta-analyze macronutrient and energy intakes during pregnancy.

METHODS

A systematic review and meta-analysis was carried out based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The required data were collected from four databases including: Web of Sciences, ProQuest, Scopus, and PubMed, from 1 January 1980 to 30 May 2023, by using a combination of search terms (dietary pattern" OR "diet quality" OR "food habits" OR "nutrition surveys" OR "diet surveys" OR "food-frequency questionnaire" OR "diet record" OR "dietary recall") AND ( "pregnancy" OR "reproduction" OR "maternal health" OR "neonatal outcomes") among interventional and observational studies. Excel and STATA version 11 were used for data analysis.

RESULTS

Among 7081 published articles, 54 studies were included in the review. Most of the 33 (61%) studies were cohort studies and a total of 135,566 pregnant women were included. The overall average of energy, carbohydrate, fat, and protein intake was 2036.10 kcal/day, 262.17 gr/day, 74.17 gr/day, and 78.21 gr/day, respectively. Also, energy intake during pregnancy was higher in American (2228.31 kcal/day, CI95%: 2135.06-2325.63) and Eastern Mediterranean regions (2226.70 kcal/day, CI95%: 2077.23-2386.92) than other regions (P < 0.001). Energy intake was higher in the third trimester than others (2115.64 kcal/day, CI95%: 1974.15-2267.27). Furthermore, based on the findings, there was a significant difference between energy intake in different World Health Organization (WHO) regions (P < 0.05).

CONCLUSIONS

According to the results of meta-analysis, the average total energy was below than average total energy required during pregnancy. More efforts are needed to encourage women to adopt healthy eating habits during pregnancy to support healthy fetal and infant development.

Nutrient regulation of development and cell fate decisions

Diet contributes to health at all stages of life, from embryonic development to old age. Nutrients, including vitamins, amino acids, lipids and sugars, have instructive roles in directing cell fate and function, maintaining stem cell populations, tissue homeostasis and alleviating the consequences of aging. This Review highlights recent findings that illuminate how common diets and specific nutrients impact cell fate decisions in healthy and disease contexts. We also draw attention to new models, technologies and resources that help to address outstanding questions in this emerging field and may lead to dietary approaches that promote healthy development and improve disease treatments.

Food taboos during pregnancy: meta-analysis on cross cultural differences suggests specific, diet-related pressures on childbirth among agriculturalists

Pregnancy is the most delicate stage of human life history as well as a common target of food taboos across cultures. Despite puzzling evidence that many pregnant women across the world reduce their intake of nutritious foods to accomplish cultural norms, no study has provided statistical analysis of cross-cultural variation in food taboos during pregnancy. Moreover, antenatal practices among forager and agriculturalists have never been compared, despite subsistence mode being known to affect staple foods and lifestyle directly. This gap hinders to us from understanding the overall threats attributed to pregnancy, and their perceived nutritional causes around the world. The present study constitutes the first cross-cultural meta-analysis on food taboos during pregnancy. We examined thirty-two articles on dietary antenatal restrictions among agricultural and non-agricultural societies, in order to: (i) identify cross-culturally targeted animal, plant and miscellaneous foods; (ii) define major clusters of taboo focus; (iii) test the hypothesis that food types and clusters of focus distribute differently between agricultural and non-agricultural taboos; and (iv) test the hypothesis that food types distribute differently across the clusters of taboo focus. All data were analysed in SPSS and RStudio using chi-squared tests and Fisher's exact tests. We detected a gradient in taboo focus that ranged from no direct physiological interest to the fear of varied physiological complications to a very specific concern over increased birth weight and difficult delivery. Non-agricultural taboos were more likely to target non-domesticated animal foods and to be justified by concerns not directly linked to the physiological sphere, whereas agricultural taboos tended to targed more cultivated and processed products and showed a stronger association with concerns over increased birth weight. Despite some methodological discrepancies in the existing literature on food taboos during pregnancy, our results illustrate that such cultural traits are useful for detecting perception of biological pressures on reproduction across cultures. Indeed, the widespread concern over birth weight and carbohydrate rich foods overlaps with clinical evidence that obstructed labor is a major threat to maternal life in Africa, Asia and Eurasia. Furthermore, asymmetry in the frequency of such concern across subsistence modes aligns with the evolutionary perspective that agriculture may have exacerbated delivery complications. This study highlights the need for the improved understanding of dietary behaviors during pregnancy across the world, addressing the role of obstructed labor as a key point of convergence between clinical, evolutionary and cultural issues in human behavior.

Association of hyperglycaemia with the placenta of GDM-induced macrosomia with normal pre-pregnancy BMI and the proliferation of trophoblast cells

The aim of this study was to identify the effect of hyperglycaemia on placentas of gestational diabetes mellitus (GDM) women with macrosomia and normal pre-pregnancy body mass index (BMI), and uncover the molecular mechanism of hyperglycaemia on trophoblast cells in vitro. GDM women with normal pre-pregnancy BMI were divided into GM group (macrosomia, n = 30) and GN group (normal birth weight, n = 35). The study showed GM group had more adverse pregnancy outcomes and higher levels of gestational weight gain, blood glucose and triglyceride. After adjustment for confounding factors, just the fasting plasma glucose level and HbA1c percentage were related to the incidence of GDM-induced macrosomia with normal pre-pregnancy BMI. Meanwhile, the fasting blood glucose was closely related to the placental weight and placental PCNA expression. Furthermore, the in vitro model for placenta showed that hyperglycaemia significantly promoted trophoblast cell proliferation and activated ERK1/2 phosphorylation. ERK1/2 inhibitor markedly suppressed hyperglycaemia-induced trophoblastic proliferation. The fasting plasma glucose and placenta are closely related with the development of GDM-induced macrosomia with normal pre-pregnancy BMI. The mechanism may be hyperglycaemia promotes trophoblast cell proliferation via ERK1/2 signalling. It provides scientific evidence for optimising outcomes of GDM women with normal pre-pregnancy BMI.IMPACT STATEMENTWhat is already known on this subject? Gestational diabetes mellitus (GDM) is one of the strongest risk factors correlated with macrosomia. The hyperglycaemic intrauterine environment affects not only the foetus but also the placental development and function in humans and experimental rodents. However, placental abnormalities associated with maternal diabetes have been inconsistently reported, possibly because of population differences in pre-pregnancy weight, diabetes types, glycemic control or pregnancy complication, and the molecular mechanism of hyperglycaemia on trophoblast cells in vitro was not clearly stated.What do the results of this study add? This is the first study to identify the effect of hyperglycaemia on placentas of gestational diabetes mellitus (GDM) women with macrosomia and normal pre-pregnancy body mass index (BMI), and uncover the molecular mechanism of hyperglycaemia on trophoblast cells in vitro.What are the implications of these findings for clinical practice and/or further research? Understanding placental changes in the environment of abnormal glucose metabolism which can establish the maternal-placental-foetal interface dysfunction as a potential source of adverse pregnancy outcomes is very necessary. Our study found the fasting plasma glucose and placenta are closely related with the development of GDM-induced macrosomia with normal pre-pregnancy BMI. The mechanism may be hyperglycaemia promotes trophoblast cell proliferation via ERK1/2 signalling. It provides scientific evidence for optimising outcomes of GDM women with normal pre-pregnancy BMI, and could be used for the following studies of relationship between placenta and childhood complications.

Ketogenic diet impairs neurological development of neonatal rats and affects biochemical composition of maternal brains: evidence of functional recovery in pups

The ketogenic diet (KD) is a type of diet in which the intake of fats significantly increases at the cost of carbohydrates while maintaining an adequate amount of proteins. This kind of diet has been successfully used in clinical therapies of drug-resistant epilepsy, but there is still insufficient evidence on its safety when used in pregnancy. To assess KD effects on the course of gestation and fetal development, pregnant females were fed with: (i) KD during pregnancy and lactation periods (KD group), (ii) KD during pregnancy replaced with ND from the day 2 postpartum (KDND group) and (iii) normal diet alone (ND group). The body mass, ketone and glucose blood levels, and food intake were monitored. In brains of KD-fed females, FTIR biochemical analyses revealed increased concentrations of lipids and ketone groups containing molecules. In offspring of these females, significant reduction of the body mass and delays in neurological development were detected. However, replacement of KD with ND in these females at the beginning of lactation period led to regainment of the body mass in their pups as early as on the postnatal day 14. Moreover, the vast majority of our neurological tests detected functional recovery up to the normal level. It could be concluded that the ketogenic diet undoubtedly affects the brain of pregnant females and impairs the somatic and neurological development of their offspring. However, early postnatal withdrawal of this diet may initiate compensatory processes and considerable functional restitution of the nervous system based on still unrecognized mechanisms.

Reconstructing Neanderthal diet: The case for carbohydrates

Evidence for plants rarely survives on Paleolithic sites, while animal bones and biomolecular analyses suggest animal produce was important to hominin populations, leading to the perspective that Neanderthals had a very-high-protein diet. But although individual and short-term survival is possible on a relatively low-carbohydrate diet, populations are unlikely to have thrived and reproduced without plants and the carbohydrates they provide. Today, nutritional guidelines recommend that around half the diet should be carbohydrate, while low intake is considered to compromise physical performance and successful reproduction. This is likely to have been the same for Paleolithic populations, highlighting an anomaly in that the basic physiological recommendations do not match the extensive archaeological evidence. Neanderthals had large, energy-expensive brains and led physically active lifestyles, suggesting that for optimal health they would have required high amounts of carbohydrates. To address this anomaly, we begin by outlining the essential role of carbohydrates in the human reproduction cycle and the brain and the effects on physical performance. We then evaluate the evidence for resource availability and the archaeological evidence for Neanderthal diet and investigate three ways that the anomaly between the archaeological evidence and the hypothetical dietary requirements might be explained. First, Neanderthals may have had an as yet unidentified genetic adaptation to an alternative physiological method to spare blood glucose and glycogen reserves for essential purposes. Second, they may have existed on a less-than-optimum diet and survived rather than thrived. Third, the methods used in dietary reconstruction could mask a complex combination of dietary plant and animal proportions. We end by proposing that analyses of Paleolithic diet and subsistence strategies need to be grounded in the minimum recommendations throughout the life course and that this provides a context for interpretation of the archaeological evidence from the behavioral and environmental perspectives.

The Legacy of Pregnancy: Elite Athletes and Women in Arduous Occupations

ABSTRACT

Best-practice guidance and management of pregnant and postpartum elite athletes and women in arduous occupations is limited by the lack of high-quality evidence available within these populations. We have summarised the adaptations and implications of pregnancy and childbirth; proposed a novel integrative concept to address these changes; and made recommendations to progress research in this area.

The obstetrical dilemma hypothesis: there's life in the old dog yet

The term 'obstetrical dilemma' was coined by Washburn in 1960 to describe the trade-off between selection for a larger birth canal, permitting successful passage of a big-brained human neonate, and the smaller pelvic dimensions required for bipedal locomotion. His suggested solution to these antagonistic pressures was to give birth prematurely, explaining the unusual degree of neurological and physical immaturity, or secondary altriciality, observed in human infants. This proposed trade-off has traditionally been offered as the predominant evolutionary explanation for why human childbirth is so challenging, and inherently risky, compared to that of other primates. This perceived difficulty is likely due to the tight fit of fetal to maternal pelvic dimensions along with the convoluted shape of the birth canal and a comparatively low degree of ligamentous flexibility. Although the ideas combined under the obstetrical dilemma hypothesis originated almost a century ago, they have received renewed attention and empirical scrutiny in the last decade, with some researchers advocating complete rejection of the hypothesis and its assumptions. However, the hypothesis is complex because it presently captures several, mutually non-exclusive ideas: (i) there is an evolutionary trade-off resulting from opposing selection pressures on the pelvis; (ii) selection favouring a narrow pelvis specifically derives from bipedalism; (iii) human neonates are secondarily altricial because they are born relatively immature to ensure that they fit through the maternal bony pelvis; (iv) as a corollary to the asymmetric selection pressure for a spacious birth canal in females, humans evolved pronounced sexual dimorphism of pelvic shape. Recently, the hypothesis has been challenged on both empirical and theoretical grounds. Here, we appraise the original ideas captured under the 'obstetrical dilemma' and their subsequent evolution. We also evaluate complementary and alternative explanations for a tight fetopelvic fit and obstructed labour, including ecological factors related to nutrition and thermoregulation, constraints imposed by the stability of the pelvic floor or by maternal and fetal metabolism, the energetics of bipedalism, and variability in pelvic shape. This reveals that human childbirth is affected by a complex combination of evolutionary, ecological, and biocultural factors, which variably constrain maternal pelvic form and fetal growth. Our review demonstrates that it is unwarranted to reject the obstetrical dilemma hypothesis entirely because several of its fundamental assumptions have not been successfully discounted despite claims to the contrary. As such, the obstetrical dilemma remains a tenable hypothesis that can be used productively to guide evolutionary research.

Exercise during Pregnancy: Developmental Programming Effects and Future Directions in Humans

Epidemiological studies show that low birth weight is associated with mortality from cardiovascular disease in adulthood, indicating that chronic diseases could be influenced by hormonal or metabolic insults encountered in utero. This concept, now known as the Developmental Origins of Health and Disease hypothesis, postulates that the intrauterine environment may alter the structure and function of the organs of the fetus as well as the expression of genes that impart an increased vulnerability to chronic diseases later in life. Lifestyle interventions initiated during the prenatal period are crucial as there is the potential to attenuate progression towards chronic diseases. However, how lifestyle interventions such as physical activity directly affect human offspring metabolism and the potential mechanisms involved in regulating metabolic balance at the cellular level are not known. The purpose of this review is to highlight the effects of exercise during pregnancy on offspring metabolic health and emphasize gaps in the current human literature and suggestions for future research.

Associations between preconception macronutrient intake and birth weight across strata of maternal BMI

INTRODUCTION

Maternal nutrition during pregnancy is linked with birth outcomes including fetal growth, birth weight, congenital anomalies and long-term health through intra-uterine programming. However, a woman's nutritional status before pregnancy is a strong determinant in early embryo-placental development, and subsequently outcomes for both mother and child. Therefore, the aim of this study was to investigate the association between dietary macronutrient intake in the preconception period with birth weight.

METHODS

We studied a group of 1698 women from the Dutch Perined-Lifelines linked birth cohort with reliable detailed information on preconception dietary macronutrient intake (using a semi quantitative food frequency questionnaire) and data available on birth weight of the offspring. Birth weight was converted into gestational age adjusted z-scores, and macronutrient intake was adjusted for total energy intake using the nutrient residual method. Preconception BMI was converted into cohort-based quintiles. Multivariable linear regression was performed, adjusted for other macronutrients and covariates.

RESULTS

Mean maternal age was 29.5 years (SD 3.9), preconception BMI: 24.7 kg/m2 (SD 4.2) and median daily energy intake was 1812 kcal (IQR 1544-2140). Mean birth weight was 3578 grams (SD 472). When adjusted for covariates, a significant association (adjusted z score [95% CI], P) between polysaccharides and birth weight was shown (0.08 [0.01-0.15], 0.03). When linear regression analyses were performed within cohort-based quintiles of maternal BMI, positive significant associations between total protein, animal protein, fat, total carbohydrates, mono-disaccharides and polysaccharides with birth weight were shown in the lowest quintile of BMI independent of energy intake, intake of other macronutrients and covariates.

CONCLUSION

Out of all macronutrients studied, polysaccharides showed the strongest association with birth weight, independent of energy intake and other covariates. Our study might suggest that specifically in women with low preconception BMI a larger amount of macronutrient intake was associated with increased birth weight. We recommend that any dietary assessment and advise during preconception should be customized to preconception weight status of the women.

Development of Obesity: The Driver and the Passenger

Obesity has reached epidemic proportions and is one of the greatest challenges for public health in the twenty-first century. The macronutrient composition of diets, in particular the amount and ratio of carbohydrates, fat and protein, have received considerable attention in recent decades due to its potential relevance to the development of obesity and weight loss. The effects of various macronutrients on body weight regulation are still under debate. High-carbohydrate diets, and particularly high-fat diets, have been blamed for the increase in the prevalence of obesity. This paper shows that neither fat nor carbohydrates are fattening per se. Mixed diets with substantial amounts of fat and high-glycemic carbohydrates, like current WDs, are required to promote weight gain and obesity. High-glycemic carbohydrates are the active partner (the "driver"), which promotes fat storage through its insulinogenic effect, while fat is the passive partner (the "passenger") on the way to obesity. Elevated insulin levels (postprandial, but more importantly due to hypersecretion and hyperinsulinemia) promote fat storage and play a key role in obesogenesis and the obesity epidemic. Furthermore, mixed diets high in high-glycemic carbohydrates and fat promote fetal programming, with long-term adverse impacts on the offspring, including insulin hypersecretion, (childhood) obesity and metabolic diseases. Maternal obesity and high weight gain during pregnancy have also been linked to deleterious effects on fetal programming. As the global obesity epidemic increasingly affects women of reproductive age, a significant percentage of fetuses will experience fetal programming with a tendency towards obesity - a self-reinforcing process that further fuels the epidemic. A change in lifestyle and diet composition is needed to prevent or limit the development of obesity and related diseases.

Factors associated with dietary glycemic index and glycemic load in pregnant women and risk for gestational diabetes mellitus

The risk of gestational diabetes mellitus (GDM) increases during the second trimester of pregnancy. However, the role of dietary glycemic index (GI) and glycemic load (GL) on GDM risk is controversial. We aimed to determine the association of established risk factors of GDM with GI and GL among healthy pregnant women, and whether GI and GL were subsequently related to GDM risk. Dietary GI and GL were assessed in healthy pregnant women from the Seremban Cohort Study using a food frequency questionnaire. After adjusting for energy intake, high GI was significantly associated with lower household income, shorter stature, higher proportion of carbohydrate intake, lower sugar proportion and lower fibre intake. High GL was significantly associated with younger maternal age, higher carbohydrate proportion and lower fibre intake. GI and GL intakes were not significantly associated with GDM risk. However, they were associated with a few established risk factors of GDM.

A Slow-Digesting Carbohydrate Diet during Rat Pregnancy Protects Offspring from Non-Alcoholic Fatty Liver Disease Risk through the Modulation of the Carbohydrate-Response Element and Sterol Regulatory Element Binding Proteins

High-fat (HF) and rapid digestive (RD) carbohydrate diets during pregnancy promote excessive adipogenesis in offspring. This effect can be corrected by diets with similar glycemic loads, but low rates of carbohydrate digestion. However, the effects of these diets on metabolic programming in the livers of offspring, and the liver metabolism contributions to adipogenesis, remain to be addressed. In this study, pregnant insulin-resistant rats were fed high-fat diets with similar glycemic loads but different rates of carbohydrate digestion, High Fat-Rapid Digestive (HF–RD) diet or High Fat-Slow Digestive (HF–SD) diet. Offspring were fed a standard diet for 10 weeks, and the impact of these diets on the metabolic and signaling pathways involved in liver fat synthesis and storage of offspring were analyzed, including liver lipidomics, glycogen and carbohydrate and lipid metabolism key enzymes and signaling pathways. Livers from animals whose mothers were fed an HF–RD diet showed higher saturated triacylglycerol deposits with lower carbon numbers and double bond contents compared with the HF–SD group. Moreover, the HF–RD group exhibited enhanced glucose transporter 2, pyruvate kinase (PK), acetyl coenzyme A carboxylase (ACC) and fatty acid (FA) synthase expression, and a decrease in pyruvate carboxylase (PyC) expression leading to an altered liver lipid profile. These parameters were normalized in the HF–SD group. The changes in lipogenic enzyme expression were parallel to changes in AktPKB phosphorylation status and nuclear expression in carbohydrate-response element and sterol regulatory element binding proteins. In conclusion, an HF–RD diet during pregnancy translates to changes in liver signaling and metabolic pathways in offspring, enhancing liver lipid storage and synthesis, and therefore non-alcoholic fatty liver disease (NAFLD) risk. These changes can be corrected by feeding an HF–SD diet during pregnancy.

Effects of Maternal Carbohydrate and Fat Intake on Fetal Telomere Length

OBJECTIVES

Telomere length can be affected by dietary factors in adults. We investigated the association between maternal carbohydrate and fat intake during pregnancy and telomere length in neonatal cord blood leukocytes. We hypothesized that high fat consumption and high carbohydrate consumption would be associated with shortened fetal telomere length.

METHODS

We collected umbilical cord blood at delivery from women admitted for labor and delivery in a university hospital (N = 62) and extracted genomic DNA using quantitative polymerase chain reaction. We quantified telomere length using the telomere-to-single copy gene ratio method (T:S ratio). High carbohydrate intake was defined as consumption of >175 g/day and high fat intake as >35 g/day. We performed generalized linear regression modeling and bootstrap statistical analyses to derive precise estimates of association.

RESULTS

Of the 62 maternal-fetal dyads included in this study, 79% were classified as high carbohydrate consumers and 37% were classified as high fat consumers. High fat consumption had a significant negative effect on T:S ratio (P < 0.05). Although high carbohydrate consumption was associated with a decreased T:S ratio, this relation did not attain statistical significance.

CONCLUSIONS

To our knowledge, this study is the first evidence of an association between maternal high fat consumption and shortened fetal telomere length. These findings could enhance our understanding of the role of maternal diet in fetal programming.

Macronutrient and Micronutrient Intake during Pregnancy: An Overview of Recent Evidence

Nutritional status during pregnancy can have a significant impact on maternal and neonatal health outcomes. Requirements for macronutrients such as energy and protein increase during pregnancy to maintain maternal homeostasis while supporting foetal growth. Energy restriction can limit gestational weight gain in women with obesity; however, there is insufficient evidence to support energy restriction during pregnancy. In undernourished women, balanced energy/protein supplementation may increase birthweight whereas high protein supplementation could have adverse effects on foetal growth. Modulating carbohydrate intake via a reduced glycaemic index or glycaemic load diet may prevent gestational diabetes and large-for-gestational-age infants. Certain micronutrients are also vital for improving pregnancy outcomes, including folic acid to prevent neural tube defects and iodine to prevent cretinism. Newly published studies support the use of calcium supplementation to prevent hypertensive disorders of pregnancy, particularly in women at high risk or with low dietary calcium intake. Although gaps in knowledge remain, research linking nutrition during pregnancy to maternofoetal outcomes has made dramatic advances over the last few years. In this review, we provide an overview of the most recent evidence pertaining to macronutrient and micronutrient requirements during pregnancy, the risks and consequences of deficiencies and the effects of supplementation on pregnancy outcomes.

Could the high consumption of high glycaemic index carbohydrates and sugars, associated with the nutritional transition to the Western type of diet, be the common cause of the obesity epidemic and the worldwide increasing incidences of Type 1 and Type 2 diabetes?

The globally increasing incidences of Type 1 diabetes (T1DM) and Type 2 diabetes (T2DM) can have a common background. If challenged by the contemporary high level of nutritional glucose stimulation, the β-cells in genetically predisposed individuals are at risk for damage which can lead to the diseases. The fat to carbohydrate dietary shift can also contribute to the associated obesity epidemic.

Impact of prenatal exercise on neonatal and childhood outcomes: a systematic review and meta-analysis

Objective

We aimed to identify the relationship between maternal prenatal exercise and birth complications, and neonatal and childhood morphometric, metabolic and developmental outcomes.

Design

Systematic review with random-effects meta-analysis and meta-regression.

Data sources

Online databases were searched up to 6 January 2017.

Study eligibility criteria

Studies of all designs were eligible (except case studies and reviews) if published in English, Spanish or French, and contained information on the relevant population (pregnant women without contraindication to exercise), intervention (subjective/objective measures of frequency, intensity, duration, volume or type of exercise, alone (‘exercise-only’) or in combination with other intervention components (eg, dietary; ‘exercise+cointervention’)), comparator (no exercise or different frequency, intensity, duration, volume, type or trimester of exercise) and outcomes (preterm birth, gestational age at delivery, birth weight, low birth weight (<2500 g), high birth weight (>4000 g), small for gestational age, large for gestational age, intrauterine growth restriction, neonatal hypoglycaemia, metabolic acidosis (cord blood pH, base excess), hyperbilirubinaemia, Apgar scores, neonatal intensive care unit admittance, shoulder dystocia, brachial plexus injury, neonatal body composition (per cent body fat, body weight, body mass index (BMI), ponderal index), childhood obesity (per cent body fat, body weight, BMI) and developmental milestones (including cognitive, psychosocial, motor skills)).

Results

A total of 135 studies (n=166 094) were included. There was ‘high’ quality evidence from exercise-only randomised controlled trials (RCTs) showing a 39% reduction in the odds of having a baby >4000 g (macrosomia: 15 RCTs, n=3670; OR 0.61, 95% CI 0.41 to 0.92) in women who exercised compared with women who did not exercise, without affecting the odds of growth-restricted, preterm or low birth weight babies. Prenatal exercise was not associated with the other neonatal or infant outcomes that were examined.

Conclusions

Prenatal exercise is safe and beneficial for the fetus. Maternal exercise was associated with reduced odds of macrosomia (abnormally large babies) and was not associated with neonatal complications or adverse childhood outcomes.

Treatments for women with gestational diabetes mellitus: an overview of Cochrane systematic reviews

BACKGROUND

Successful treatments for gestational diabetes mellitus (GDM) have the potential to improve health outcomes for women with GDM and their babies.

OBJECTIVES

To provide a comprehensive synthesis of evidence from Cochrane systematic reviews of the benefits and harms associated with interventions for treating GDM on women and their babies.

METHODS

We searched the Cochrane Database of Systematic Reviews (5 January 2018) for reviews of treatment/management for women with GDM. Reviews of pregnant women with pre-existing diabetes were excluded.Two overview authors independently assessed reviews for inclusion, quality (AMSTAR; ROBIS), quality of evidence (GRADE), and extracted data.

MAIN RESULTS

We included 14 reviews. Of these, 10 provided relevant high-quality and low-risk of bias data (AMSTAR and ROBIS) from 128 randomised controlled trials (RCTs), 27 comparisons, 17,984 women, 16,305 babies, and 1441 children. Evidence ranged from high- to very low-quality (GRADE). Only one effective intervention was found for treating women with GDM.EffectiveLifestyle versus usual careLifestyle intervention versus usual care probably reduces large-for-gestational age (risk ratio (RR) 0.60, 95% confidence interval (CI) 0.50 to 0.71; 6 RCTs, N = 2994; GRADE moderate-quality).PromisingNo evidence for any outcome for any comparison could be classified to this category.Ineffective or possibly harmful Lifestyle versus usual careLifestyle intervention versus usual care probably increases the risk of induction of labour (IOL) suggesting possible harm (average RR 1.20, 95% CI 0.99 to 1.46; 4 RCTs, N = 2699; GRADE moderate-quality).Exercise versus controlExercise intervention versus control for return to pre-pregnancy weight suggested ineffectiveness (body mass index, BMI) MD 0.11 kg/m², 95% CI -1.04 to 1.26; 3 RCTs, N = 254; GRADE moderate-quality).Insulin versus oral therapyInsulin intervention versus oral therapy probably increases the risk of IOL suggesting possible harm (RR 1.3, 95% CI 0.96 to 1.75; 3 RCTs, N = 348; GRADE moderate-quality).Probably ineffective or harmful interventionsInsulin versus oral therapyFor insulin compared to oral therapy there is probably an increased risk of the hypertensive disorders of pregnancy (RR 1.89, 95% CI 1.14 to 3.12; 4 RCTs, N = 1214; GRADE moderate-quality).InconclusiveLifestyle versus usual careThe evidence for childhood adiposity kg/m² (RR 0.91, 95% CI 0.75 to 1.11; 3 RCTs, N = 767; GRADE moderate-quality) and hypoglycaemia was inconclusive (average RR 0.99, 95% CI 0.65 to 1.52; 6 RCTs, N = 3000; GRADE moderate-quality).Exercise versus controlThe evidence for caesarean section (RR 0.86, 95% CI 0.63 to 1.16; 5 RCTs, N = 316; GRADE moderate quality) and perinatal death or serious morbidity composite was inconclusive (RR 0.56, 95% CI 0.12 to 2.61; 2 RCTs, N = 169; GRADE moderate-quality).Insulin versus oral therapyThe evidence for the following outcomes was inconclusive: pre-eclampsia (RR 1.14, 95% CI 0.86 to 1.52; 10 RCTs, N = 2060), caesarean section (RR 1.03, 95% CI 0.93 to 1.14; 17 RCTs, N = 1988), large-for-gestational age (average RR 1.01, 95% CI 0.76 to 1.35; 13 RCTs, N = 2352), and perinatal death or serious morbidity composite (RR 1.03; 95% CI 0.84 to 1.26; 2 RCTs, N = 760). GRADE assessment was moderate-quality for these outcomes.Insulin versus dietThe evidence for perinatal mortality was inconclusive (RR 0.74, 95% CI 0.41 to 1.33; 4 RCTs, N = 1137; GRADE moderate-quality).Insulin versus insulinThe evidence for insulin aspart versus lispro for risk of caesarean section was inconclusive (RR 1.00, 95% CI 0.91 to 1.09; 3 RCTs, N = 410; GRADE moderate quality).No conclusions possibleNo conclusions were possible for: lifestyle versus usual care (perineal trauma, postnatal depression, neonatal adiposity, number of antenatal visits/admissions); diet versus control (pre-eclampsia, caesarean section); myo-inositol versus placebo (hypoglycaemia); metformin versus glibenclamide (hypertensive disorders of pregnancy, pregnancy-induced hypertension, death or serious morbidity composite, insulin versus oral therapy (development of type 2 diabetes); intensive management versus routine care (IOL, large-for-gestational age); post- versus pre-prandial glucose monitoring (large-for-gestational age). The evidence ranged from moderate-, low- and very low-quality.

AUTHORS' CONCLUSIONS

Currently there is insufficient high-quality evidence about the effects on health outcomes of relevance for women with GDM and their babies for many of the comparisons in this overview comparing treatment interventions for women with GDM. Lifestyle changes (including as a minimum healthy eating, physical activity and self-monitoring of blood sugar levels) was the only intervention that showed possible health improvements for women and their babies. Lifestyle interventions may result in fewer babies being large. Conversely, in terms of harms, lifestyle interventions may also increase the number of inductions. Taking insulin was also associated with an increase in hypertensive disorders, when compared to oral therapy. There was very limited information on long-term health and health services costs. Further high-quality research is needed.

Feeding a slowly digestible carbohydrate diet during pregnancy of insulin-resistant rats prevents the excess of adipogenesis in their offspring

An obesogenic environment during pregnancy has been shown to increase the risk of dysregulation on adipogenesis and insulin resistance in the offspring. Being essential for the growing fetus, glucose supply is guaranteed by a number of modifications in the mother's metabolism, and thus, glucose control during pregnancy especially among obese or diabetic women is paramount to prevent adverse consequences in their children. Besides the election of low-glycemic-index carbohydrates, the rate of carbohydrate digestion could be relevant to keep a good glucose control. In the present study, we compared the effects of two high-fat diets with similar glycemic load but different rates of carbohydrate digestion given to pregnant insulin-resistant rats. After birth, all animals were fed a standard diet until age 14 weeks. We analyzed offspring body composition, plasma and adipocyte lipidomics, lipid metabolism in adipose tissue and insulin sensitivity. Those animals whose mothers were fed the rapid-digesting carbohydrate diet exhibited an excessive adipogenesis. Thus, these animals showed a marked lipidemia, increased lipid synthesis in the adipose tissue and reduced glucose transporter amount in the adipose. On the contrary, those animals whose mothers were fed the slow-digesting carbohydrate diet showed a profile in the measured parameters closer to that of the offspring of healthy mothers. These results support the hypothesis that not only glycemic index but the rate of carbohydrate digestion during gestation may be critical to regulate the programming of adipogenesis in the offspring.

Temporal relationships of GH, IGF-I and fructosamine concentrations in pregnant Spanish Purebred mares: A substantial contribution from the hormonal standpoint

Growth hormone (GH) and insulin-like growth factor (IGF-I) exert essential functions to maintain an adequate metabolic activity for correct placental and fetal development. Although fructosamine (FRUCT) is used in clinical evaluation to assess the glycaemic state, the relationships between GH, IGF-I and FRUCT remain unknown in the mare. Therefore, the objectives of this study were to evaluate the relationships among these parameters in pregnant mares. A total of 30 healthy Spanish Purebred mares, with an age range of 9.33 ± 3.31 years, were studied during the 11 months of gestation. Serum concentrations of GH, IGF-I and FRUCT were analyzed by EIA, competition ELISA and spectrophotometry, respectively. GH showed a biphasic pattern, the first occurred during 4th and 5th month and the second which was higher than the 1st one during the 7th, 8th and 9th month (P < 0.05). Compared to the 1st month, the IGF-I concentrations increased in the 2nd month (P < 0.05), decreased in the 3rd and 4th month and increased to reach the maximum average value in the 5th month (P < 0.05); after slight oscillations between the 6th and 8th month, IGF-I concentrations increased in the 9th month (P < 0.05), decreasing until the end of gestation. FRUCT increased progressively and significantly from the 6th month of gestation, reaching the maximum values in the last month of gestation (P < 0.05). These results suggest that alternative mechanisms other than GH and IGF-I could be involved in the regulation of glycaemic metabolism in pregnant mare.

Modern dietary guidelines for healthy pregnancy; maximising maternal and foetal outcomes and limiting excessive gestational weight gain

Maternal dietary habits influence maternal and foetal health, representing a pathway for intervention to maximise pregnancy outcomes. Advice on energy intake is provided on a trimester basis, with no additional calories required in the first trimester and an additional 340 kcal d^-1 and 452 kcal d^-1 needed for the second and third trimesters. Energy intake depends on pre-gravid body mass index (BMI); underweight women are recommended an increase of 150, 200 and 300 kcal d^-1 during the first, second and third trimester, normal weight women an increase of 0, 350 and 500 kcal d^-1 and obese women an increase of 0, 450 and 350 kcal day^-1. The recommendations for carbohydrate and protein intake are 175 g d^-1 and 0.88-1.1 g kgBM d^-1, with no change to fat intake. The number of pre-gravid obese women is rising; therefore, we need to regulate weight in women of childbearing age and limit gestational weight gain to within the recommended ranges [overweight women 6.8-11.3 kg and obese women 5.0-9.1 kg]. This can be achieved using nutritional interventions, as dietary changes have been shown to help with gestational weight management. As pregnancy has been identified as a risk factor for the development of obesity, normal weight women should gain 11.5-16.0 kg during pregnancy. While some research has shown that dietary interventions help to regulate gestational weight gain and promote postpartum weight loss to some extent, future research is needed to provide safe and effective guidelines to maximise these effects, while benefitting maternal and foetal health.

Is dietary macronutrient composition during pregnancy associated with offspring birth weight? An observational study

There is lack of evidence on the differential impact of maternal macronutrient consumption: carbohydrates (CHO), fats and protein on birth weight. We investigated the association between maternal dietary macronutrient intakes and their sub-components such as saccharides and fatty acids and birth weight. This analyses included 1,196 women with singleton pregnancies who were part of the CAffeine and REproductive health study in Leeds, UK between 2003 and 2006. Women were interviewed in each trimester. Dietary information was collected twice using a 24-h dietary recall about 8–12 weeks and 13–27 weeks of gestation. Multiple linear regression models adjusted for alcohol and smoking in trimester 1, showed that each additional 10 g/d CHO consumption was associated with an increase of 4 g (95 % CI 1, 7;P=0·003) in birth weight. Conversely, an additional 10 g/d fat intake was associated with a lower birth weight of 8 g (95 % CI 0, 16;P=0·04) when we accounted for energy contributing macronutrients in each model, and maternal height, weight, parity, ethnicity, gestational age at delivery and sex of the baby. There was no evidence of an association between protein intake and birth weight. Maternal diet in trimester 2 suggested that higher intakes of glucose (10 g/d) and lactose (1 g/d) were both associated with higher birth weight of 52 g (95 % CI 4, 100;P=0·03) and 5 g (95 % CI 2, 7;P<0·001) respectively. These results show that dietary macronutrient composition during pregnancy is associated with birth weight outcomes. An appropriately balanced intake of dietary CHO and fat during pregnancy could support optimum birth weight.

Combined diet and exercise interventions for preventing gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a wide range of adverse health consequences for women and their infants in the short and long term. With an increasing prevalence of GDM worldwide, there is an urgent need to assess strategies for GDM prevention, such as combined diet and exercise interventions. This is an update of a Cochrane review that was first published in 2015.

OBJECTIVES

To assess the effects of diet interventions in combination with exercise interventions for pregnant women for preventing GDM, and associated adverse health consequences for the mother and her infant/child.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 November 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and cluster-RCTs, comparing combined diet and exercise interventions with no intervention (i.e. standard care), that reported on GDM diagnosis as an outcome. Quasi-RCTs were excluded. Cross-over trials were not eligible for inclusion. We planned to include RCTs comparing two or more different diet/exercise interventions, however none were identified.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data, assessed the risk of bias of the included trials and assessed quality of evidence for selected maternal and infant/child outcomes using the GRADE approach. We checked data for accuracy.

MAIN RESULTS

In this update, we included 23 RCTs (involving 8918 women and 8709 infants) that compared combined diet and exercise interventions with no intervention (standard care). The studies varied in the diet and exercise programs evaluated and health outcomes reported. None reported receiving funding from a drug manufacturer or agency with interests in the results. Overall risk of bias was judged to be unclear due to the lack of methodological detail reported. Most studies were undertaken in high-income countries.For our primary review outcomes, there was a possible reduced risk of GDM in the diet and exercise intervention group compared with the standard care group (average risk ratio (RR) 0.85, 95% confidence interval (CI) 0.71 to 1.01; 6633 women; 19 RCTs; Tau² = 0.05; I² = 42%; P = 0.07; moderate-quality evidence). There was also a possible reduced risk of caesarean section (RR 0.95, 95% CI 0.88 to 1.02; 6089 women; 14 RCTs; moderate-quality evidence). No clear differences were seen between groups for pre-eclampsia (RR 0.98, 95% CI 0.79 to 1.22; 5366 participants; 8 RCTs; low-quality evidence), pregnancy-induced hypertension and/or hypertension (average RR 0.78, 95% CI 0.47 to 1.27; 3073 participants; 6 RCTs; Tau² = 0.19; I² = 62%; very low-quality evidence), perinatal mortality (RR 0.82, 95% CI 0.42 to 1.63; 3757 participants; 2 RCTs; low-quality evidence) or large-for-gestational age (RR 0.93, 95% CI 0.81 to 1.07; 5353 participants; 11 RCTs; low-quality evidence). No data were reported for infant mortality or morbidity composite.Subgroup analyses (based on trial design, maternal body mass index (BMI) and ethnicity) revealed no clear differential treatment effects. We were unable to assess the impact of maternal age, parity and specific features of the diet and exercise interventions. Findings from sensitivity analyses (based on RCT quality) generally supported those observed in the main analyses. We were not able to perform subgroup analyses based on maternal age, parity or nature of the exercise/dietary interventions due to the paucity of information/data on these characteristics and the inability to meaningfully group intervention characteristics.For most of the secondary review outcomes assessed using GRADE, there were no clear differences between groups, including for perineal trauma (RR 1.27, 95% CI 0.78 to 2.05; 2733 participants; 2 RCTs; moderate-quality evidence), neonatal hypoglycaemia (average RR 1.42, 95% CI 0.67 to 2.98; 3653 participants; 2 RCTs; Tau² = 0.23; I² = 77%; low quality evidence); and childhood adiposity (BMI z score) (MD 0.05, 95% CI -0.29 to 0.40; 794 participants; 2 RCTs; Tau² = 0.04; I² = 59%; low-quality evidence). However, there was evidence of less gestational weight gain in the diet and exercise intervention group compared with the control group (mean difference (MD) -0.89 kg, 95% CI -1.39 to -0.40; 5052 women; 16 RCTs; Tau² = 0.37; I² = 43%;moderate-quality evidence). No data were reported for maternal postnatal depression or type 2 diabetes; childhood/adulthood type 2 diabetes, or neurosensory disability.

AUTHORS' CONCLUSIONS

Moderate-quality evidence suggests reduced risks of GDM and caesarean section with combined diet and exercise interventions during pregnancy as well as reductions in gestational weight gain, compared with standard care. There were no clear differences in hypertensive disorders of pregnancy, perinatal mortality, large-for-gestational age, perineal trauma, neonatal hypoglycaemia, and childhood adiposity (moderate- tovery low-quality evidence).Using GRADE methodology, the evidence was assessed as moderate to very low quality. Downgrading decisions were predominantly due to design limitations (risk of bias), and imprecision (uncertain effect estimates, and at times, small sample sizes and low event rates), however two outcomes (pregnancy-induced hypertension/hypertension and neonatal hypoglycaemia), were also downgraded for unexplained inconsistency (statistical heterogeneity).Due to the variability of the diet and exercise components tested in the included studies, the evidence in this review has limited ability to inform practice. Future studies could describe the interventions used in more detail, if and how these influenced behaviour change and ideally be standardised between studies. Studies could also consider using existing core outcome sets to facilitate more standardised reporting.

A systematic review of interventions for Hispanic women with or at risk of Gestational diabetes mellitus (GDM)

BACKGROUND AND OBJECTIVE

Gestational Diabetes Mellitus (GDM) is a serious health concern for pregnant women, with Hispanic women at particular risk for developing the condition. The aim of this review was to critically examine GDM intervention programs for Hispanic women, in the United States of America (US).

METHODS

English and Spanish electronic databases were searched for relevant studies published between 1995 and 2015. Eligible study designs included randomized controlled trial, pre/post-test and quasi experimental methods.

RESULTS

Findings indicated that there was a dearth of literature reporting on GDM interventions for Hispanic women and just seven papers met inclusion criteria. These seven studies were included in the review and they reported on interventions for: (1) pregnant women at high risk of developing GDM; (2) pregnant women with GDM. Results suggest that a combination of intensive counselling over a prolonged period of time, together with a low calorie, possibly low glycemic index diet, produces best results.

CONCLUSION

The review found that intensive nutritional counselling approaches which promote low calorie/low GI diets appear to be most effective in BGL management in this population. Interventions that are delivered in Spanish and culturally tailored may be more acceptable to participants. More research is needed to develop suitable interventions to improve GDM management among Hispanic women.

Different types of dietary advice for women with gestational diabetes mellitus

BACKGROUND

Dietary advice is the main strategy for managing gestational diabetes mellitus (GDM). It remains unclear what type of advice is best.

OBJECTIVES

To assess the effects of different types of dietary advice for women with GDM for improving health outcomes for women and babies.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (8 March 2016), PSANZ's Trials Registry (22 March 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials comparing the effects of different types of dietary advice for women with GDM.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility, risk of bias, and extracted data. Evidence quality for two comparisons was assessed using GRADE, for primary outcomes for the mother: hypertensive disorders of pregnancy; caesarean section; type 2 diabetes mellitus; and child: large-for-gestational age; perinatal mortality; neonatal mortality or morbidity composite; neurosensory disability; secondary outcomes for the mother: induction of labour; perineal trauma; postnatal depression; postnatal weight retention or return to pre-pregnancy weight; and child: hypoglycaemia; childhood/adulthood adiposity; childhood/adulthood type 2 diabetes mellitus.

MAIN RESULTS

In this update, we included 19 trials randomising 1398 women with GDM, at an overall unclear to moderate risk of bias (10 comparisons). For outcomes assessed using GRADE, downgrading was based on study limitations, imprecision and inconsistency. Where no findings are reported below for primary outcomes or pre-specified GRADE outcomes, no data were provided by included trials. Primary outcomes Low-moderate glycaemic index (GI) versus moderate-high GI diet (four trials): no clear differences observed for: large-for-gestational age (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.22 to 2.34; two trials, 89 infants; low-quality evidence); severe hypertension or pre-eclampsia (RR 1.02, 95% CI 0.07 to 15.86; one trial, 95 women; very low-quality evidence); eclampsia (RR 0.34, 95% CI 0.01 to 8.14; one trial, 83 women; very low-quality evidence) or caesarean section (RR 0.66, 95% CI 0.29 to 1.47; one trial, 63 women; low-quality evidence). Energy-restricted versus no energy-restricted diet (three trials): no clear differences seen for: large-for-gestational age (RR 1.17, 95% CI 0.65 to 2.12; one trial, 123 infants; low-quality evidence); perinatal mortality (no events; two trials, 423 infants; low-quality evidence); pre-eclampsia (RR 1.00, 95% CI 0.51 to 1.97; one trial, 117 women; low-quality evidence); or caesarean section (RR 1.12, 95% CI 0.80 to 1.56; two trials, 420 women; low-quality evidence). DASH (Dietary Approaches to Stop Hypertension) diet versus control diet (three trials): no clear differences observed for: pre-eclampsia (RR 1.00, 95% CI 0.31 to 3.26; three trials, 136 women); however there were fewer caesarean sections in the DASH diet group (RR 0.53, 95% CI 0.37 to 0.76; two trials, 86 women). Low-carbohydrate versus high-carbohydrate diet (two trials): no clear differences seen for: large-for-gestational age (RR 0.51, 95% CI 0.13 to 1.95; one trial, 149 infants); perinatal mortality (RR 3.00, 95% CI 0.12 to 72.49; one trial, 150 infants); maternal hypertension (RR 0.40, 95% CI 0.13 to 1.22; one trial, 150 women); or caesarean section (RR 1.29, 95% CI 0.84 to 1.99; two trials, 179 women). High unsaturated fat versus low unsaturated fat diet (two trials): no clear differences observed for: large-for-gestational age (RR 0.54, 95% CI 0.21 to 1.37; one trial, 27 infants); pre-eclampsia (no cases; one trial, 27 women); hypertension in pregnancy (RR 0.54, 95% CI 0.06 to 5.26; one trial, 27 women); caesarean section (RR 1.08, 95% CI 0.07 to 15.50; one trial, 27 women); diabetes at one to two weeks (RR 2.00, 95% CI 0.45 to 8.94; one trial, 24 women) or four to 13 months postpartum (RR 1.00, 95% CI 0.10 to 9.61; one trial, six women). Low-GI versus high-fibre moderate-GI diet (one trial): no clear differences seen for: large-for-gestational age (RR 2.87, 95% CI 0.61 to 13.50; 92 infants); caesarean section (RR 1.91, 95% CI 0.91 to 4.03; 92 women); or type 2 diabetes at three months postpartum (RR 0.76, 95% CI 0.11 to 5.01; 58 women). Diet recommendation plus diet-related behavioural advice versus diet recommendation only (one trial): no clear differences observed for: large-for-gestational age (RR 0.73, 95% CI 0.25 to 2.14; 99 infants); or caesarean section (RR 0.78, 95% CI 0.38 to 1.62; 99 women). Soy protein-enriched versus no soy protein diet (one trial): no clear differences seen for: pre-eclampsia (RR 2.00, 95% CI 0.19 to 21.03; 68 women); or caesarean section (RR 1.00, 95% CI 0.57 to 1.77; 68 women). High-fibre versus standard-fibre diet (one trial): no primary outcomes reported. Ethnic-specific versus standard healthy diet (one trial): no clear differences observed for: large-for-gestational age (RR 0.14, 95% CI 0.01 to 2.45; 20 infants); neonatal composite adverse outcome (no events; 20 infants); gestational hypertension (RR 0.33, 95% CI 0.02 to 7.32; 20 women); or caesarean birth (RR 1.20, 95% CI 0.54 to 2.67; 20 women). Secondary outcomes For secondary outcomes assessed using GRADE no differences were observed: between a low-moderate and moderate-high GI diet for induction of labour (RR 0.88, 95% CI 0.33 to 2.34; one trial, 63 women; low-quality evidence); or an energy-restricted and no energy-restricted diet for induction of labour (RR 1.02, 95% CI 0.68 to 1.53; one trial, 114 women, low-quality evidence) and neonatal hypoglycaemia (average RR 1.06, 95% CI 0.48 to 2.32; two trials, 408 infants; very low-quality evidence).Few other clear differences were observed for reported outcomes. Longer-term health outcomes and health services use and costs were largely not reported.

AUTHORS' CONCLUSIONS

Evidence from 19 trials assessing different types of dietary advice for women with GDM suggests no clear differences for primary outcomes and secondary outcomes assessed using GRADE, except for a possible reduction in caesarean section for women receiving a DASH diet compared with a control diet. Few differences were observed for secondary outcomes.Current evidence is limited by the small number of trials in each comparison, small sample sizes, and variable methodological quality. More evidence is needed to assess the effects of different types of dietary advice for women with GDM. Future trials should be adequately powered to evaluate short- and long-term outcomes.

Nutrient Intake according to Weight Gain during Pregnancy, Job Status, and Household Income

The objective of this study was to investigate the association of nutrient intake and pregnancy outcome mediated by weight gain during pregnancy, job status, and household income. Maternal age, educational level, self-reported pre-pregnancy weights, educational level, and household income were collected from the women at 2 months postpartum. For each offspring, weight at birth, length at birth, and gestational age were collected. Participants were asked to report the frequency of consumption of foods between 28–42 weeks into the pregnancy. Diet was assessed by using a validated 106-item semi-quantitative food-frequency questionnaire (SQFFQ) and women were asked portions and quantities based on pictures, food models, and measuring tools such as cups or teaspoons. Results showed that women who gained below the recommended weight gain during pregnancy, within, and over were 25.3%, 38.7%, 36.0%, respectively. In comparison to weight gain and the offspring's length and weight at birth, the offspring of mothers with a lower weight gain had a higher length. Energy, protein, vitamin B₂, vitamin C, calcium, and potassium were significantly lower at employed group. We did not observe a significant difference between birth characteristics and maternal nutrient intake by income. Infants with a higher ponderal index at birth were born to women with a higher pre-pregnancy body mass index (BMI).

Dietary advice interventions in pregnancy for preventing gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is a form of diabetes occurring during pregnancy which can result in short- and long-term adverse outcomes for women and babies. With an increasing prevalence worldwide, there is a need to assess strategies, including dietary advice interventions, that might prevent GDM.

OBJECTIVES

To assess the effects of dietary advice interventions for preventing GDM and associated adverse health outcomes for women and their babies.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (3 January 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs assessing the effects of dietary advice interventions compared with no intervention (standard care), or to different dietary advice interventions. Cluster-RCTs were eligible for inclusion but none were identified.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data and assessed the risk of bias of the included studies. Data were checked for accuracy. The quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

We included 11 trials involving 2786 women and their babies, with an overall unclear to moderate risk of bias. Six trials compared dietary advice interventions with standard care; four compared low glycaemic index (GI) with moderate- to high-GI dietary advice; one compared specific (high-fibre focused) with standard dietary advice. Dietary advice interventions versus standard care (six trials) Considering primary outcomes, a trend towards a reduction in GDM was observed for women receiving dietary advice compared with standard care (average risk ratio (RR) 0.60, 95% confidence interval (CI) 0.35 to 1.04; five trials, 1279 women; Tau² = 0.20; I² = 56%; P = 0.07; GRADE: very low-quality evidence); subgroup analysis suggested a greater treatment effect for overweight and obese women receiving dietary advice. While no clear difference was observed for pre-eclampsia (RR 0.61, 95% CI 0.25 to 1.46; two trials, 282 women; GRADE: low-quality evidence) a reduction in pregnancy-induced hypertension was observed for women receiving dietary advice (RR 0.30, 95% CI 0.10 to 0.88; two trials, 282 women; GRADE: low-quality evidence). One trial reported on perinatal mortality, and no deaths were observed (GRADE: very low-quality evidence). None of the trials reported on large-for-gestational age or neonatal mortality and morbidity.For secondary outcomes, no clear differences were seen for caesarean section (average RR 0.98, 95% CI 0.78 to 1.24; four trials, 1194 women; Tau² = 0.02; I² = 36%; GRADE: low-quality evidence) or perineal trauma (RR 0.83, 95% CI 0.23 to 3.08; one trial, 759 women; GRADE: very low-quality evidence). Women who received dietary advice gained less weight during pregnancy (mean difference (MD) -4.70 kg, 95% CI -8.07 to -1.34; five trials, 1336 women; Tau² = 13.64; I² = 96%; GRADE: low-quality evidence); the result should be interpreted with some caution due to considerable heterogeneity. No clear differences were seen for the majority of secondary outcomes reported, including childhood/adulthood adiposity (skin-fold thickness at six months) (MD -0.10 mm, 95% CI -0.71 to 0.51; one trial, 132 children; GRADE: low-quality evidence). Women receiving dietary advice had a lower well-being score between 14 and 28 weeks, more weight loss at three months, and were less likely to have glucose intolerance (one trial).The trials did not report on other secondary outcomes, particularly those related to long-term health and health service use and costs. We were not able to assess the following outcomes using GRADE: postnatal depression; maternal type 2 diabetes; neonatal hypoglycaemia; childhood/adulthood type 2 diabetes; and neurosensory disability. Low-GI dietary advice versus moderate- to high-GI dietary advice (four trials) Considering primary outcomes, no clear differences were shown in the risks of GDM (RR 0.91, 95% CI 0.63 to 1.31; four trials, 912 women; GRADE: low-quality evidence) or large-for-gestational age (average RR 0.60, 95% CI 0.19 to 1.86; three trials, 777 babies; Tau² = 0.61; P = 0.07; I² = 62%; GRADE: very low-quality evidence) between the low-GI and moderate- to high-GI dietary advice groups. The trials did not report on: hypertensive disorders of pregnancy; perinatal mortality; neonatal mortality and morbidity.No clear differences were shown for caesarean birth (RR 1.27, 95% CI 0.79 to 2.04; two trials, 201 women; GRADE: very low-quality evidence) and gestational weight gain (MD -1.23 kg, 95% CI -4.08 to 1.61; four trials, 787 women; Tau² = 7.31; I² = 90%; GRADE: very low-quality evidence), or for other reported secondary outcomes.The trials did not report the majority of secondary outcomes including those related to long-term health and health service use and costs. We were not able to assess the following outcomes using GRADE: perineal trauma; postnatal depression; maternal type 2 diabetes; neonatal hypoglycaemia; childhood/adulthood adiposity; type 2 diabetes; and neurosensory disability. High-fibre dietary advice versus standard dietary advice (one trial) The one trial in this comparison reported on two secondary outcomes. No clear difference between the high-fibre and standard dietary advice groups observed for mean blood glucose (following an oral glucose tolerance test at 35 weeks), and birthweight.

AUTHORS' CONCLUSIONS

Very low-quality evidence from five trials suggests a possible reduction in GDM risk for women receiving dietary advice versus standard care, and low-quality evidence from four trials suggests no clear difference for women receiving low- versus moderate- to high-GI dietary advice. A possible reduction in pregnancy-induced hypertension for women receiving dietary advice was observed and no clear differences were seen for other reported primary outcomes. There were few outcome data for secondary outcomes.For outcomes assessed using GRADE, evidence was considered to be low to very low quality, with downgrading based on study limitations (risk of bias), imprecision, and inconsistency.More high-quality evidence is needed to determine the effects of dietary advice interventions in pregnancy. Future trials should be designed to monitor adherence, women's views and preferences, and powered to evaluate effects on short- and long-term outcomes; there is a need for such trials to collect and report on core outcomes for GDM research. We have identified five ongoing studies and four are awaiting classification. We will consider these in the next review update.

Effects of post-suckling n-3 polyunsaturated fatty acids: prevention of dyslipidemia and liver steatosis induced in rats by a sucrose-rich diet during pre- and post-natal life

The interaction between fetal programming and the post-natal environment suggests that the post-natal diet could amplify or attenuate programmed outcomes. We investigated whether dietary n-3 long-chain polyunsaturated fatty acids (n-3 PUFAs) at weaning resulted in an amelioration of dyslipidemia, adiposity and liver steatosis that was induced by a sucrose-rich diet (SRD; where the fat source is corn oil) from the onset of pregnancy up to adulthood. During pregnancy and lactation, dams were fed an SRD or the standard powdered rodent commercial diet (RD). At weaning and until 150 days of life, male offspring from SRD-dams were divided into two groups and fed an SRD or SRD-with-fish oil [where 6% of the corn oil was partially replaced by fish oil (FO) 5% and corn oil (CO) 1%], forming SRD-SRD or SRD-FO groups. Male offspring from RD-dams continued with RD up to the end of the experimental period, forming an RD-RD group. The presence of FO in the weaning diet showed the following: prevention of hypertriglyceridemia and liver steatosis, together with increased lipogenic enzyme activity caused by a maternal SRD; the complete normalization of CPT I activity and PPARα protein mass levels; a slight but not statistically significant accretion of visceral adiposity; and limited body fat content and reduced plasma free fatty acid levels. All of these results were observed even in the presence of a high-sucrose diet challenge after weaning. SRD-dams' breast milk showed a more saturated fatty acid composition. These results suggest the capacity of n-3 PUFAs to overcome some adverse outcomes induced by a maternal and post-weaning sucrose-rich diet.

Effects of low-glycemic-index diets in pregnancy on maternal and newborn outcomes in pregnant women: a meta-analysis of randomized controlled trials

PURPOSE

Maternal diet with a high glycemic index (GI) is associated with fetal overgrowth and higher infant body adiposity. Effects of low-GI diet on maternal and newborn outcomes have been assessed in both healthy pregnancy and gestational diabetes mellitus, but the results remain inconclusive. This meta-analysis aimed to examine the effects of low-GI diets on maternal and newborn outcomes.

METHODS

PubMed, Clinical Trials, and Cochrane Library databases were searched for relevant randomized trials up to January 2016. Random- or fixed-effects models were used to calculate combined treatment effects.

RESULTS

A total of 11 trials involving 1985 women were eligible for analysis. This meta-analysis assessed 7 maternal and 11 newborn outcomes. Of these, gestational weight gain (GWG), fasting blood glucose (FBG), newborn birth weight, ponderal index (PI), proportion of macrosomia, and large for gestational age (LGA) were investigated in more than 8 trials. Compared with control diets, low-GI diets significantly reduced FBG (weight mean differences (WMD) = -0.18 mmol/L, 95 % CI: -0.33, -0.02), 2-h postprandial glucose level (WMD = -0.33 mmol/L, 95 % CI: -0.54, -0.12), and the proportion of LGA (RR = 0.52, 95 % CI: 0.31, 0.89). A lower GWG (WMD = -0.69 kg, 95 % CI: -1.74, 0.36) and birth weight (WMD = -0.10 kg, 95 % CI: -0.23, 0.03) were also observed without significant differences. Heterogeneity was observed in the GWG, FBG, and birth weight analyses. Low-GI diets did not affect other maternal and newborn outcomes. In subgroup and sensitivity analyses, the intervention effects of low GI on GWG and FBG varied.

CONCLUSIONS

Low-GI diets may have beneficial effects on maternal outcomes for those at risk of developing high glucose levels, without causing adverse effects on newborn outcomes. However, results should be interpreted with caution because of the evidence of heterogeneity and limited number of studies.

Current Concepts of Maternal Nutrition

BACKGROUND

A nutrient-rich maternal diet before and during pregnancy is associated with improved fetal health, more appropriate birth weight, and increased rates of maternal and infant survival. Physicians need a better understanding of the role of diet in shaping fetal outcomes. Given this background, we reviewed and summarized articles on maternal nutrition found in MEDLINE since 1981, written in English, and limited to human subjects.

FOR THE OFFSPRING

Maternal diets high in sugar and fat lead to an increased incidence of metabolic syndrome, diabetes, and cardiovascular disease later in life. Folic acid should be supplemented prior to conception and continued through at least the first 28 days of fetal life to prevent neural tube defects, and vitamin C should be given to women who smoke to lower the incidence of asthma and wheezing in the children. Iodine deficiency is increasing, and iodine should be included in prenatal supplements. If the maternal hemoglobin is 7 g/dL or more, there is no evidence that iron supplementation is needed. Fish intake during pregnancy is protective against atopic outcomes, whereas high-meat diets contribute to elevated adult blood pressure and hypersecretion of cortisol.

FOR THE MOTHER

Calcium supplementation lowers the risk of preeclampsia and hypertensive disease in pregnancy.

CONCLUSIONS

Given the limits of our current knowledge, a diet rich in whole grains, fruits, vegetables, and selected fish is desirable for the best outcomes. Diets high in sugar and fat lead to higher rates of diabetes, metabolic syndrome, and cardiovascular disease. Folic acid, iodine, and calcium in all pregnant women and vitamin C in smokers are the only supplements so far shown to be of value for routine use. The physician treating a pregnant woman should be ready to advise a healthy diet for the benefit of the fetus.

Fetal and maternal metabolic responses to exercise during pregnancy

Pregnancy is characterized by physiological, endocrine and metabolic adaptations creating a pseudo-diabetogenic state of progressive insulin resistance. These adaptations occur to sustain continuous fetal requirements for nutrients and oxygen. Insulin resistance develops at the level of the skeletal muscle, and maternal exercise, especially activity involving large muscle groups improve glucose tolerance and insulin sensitivity. We discuss the maternal hormonal and metabolic changes associated with a normal pregnancy, the metabolic dysregulation that may occur leading to gestational diabetes mellitus (GDM), and the consequences to mother and fetus. We will then examine the acute and chronic (training) responses to exercise in the non-pregnant state and relate these alterations to maternal exercise in a low-risk pregnancy, how exercise can be used to regulate glucose tolerance in women at risk for or diagnosed with GDM. Lastly, we present key exercise guidelines to help maintain maternal glucose regulation and suggest future research directions.

Intake of carbohydrates during pregnancy in obese women is associated with fat mass in the newborn offspring

BACKGROUND

Transmission of obesity across generations is of concern. Offspring of obese women have short- and long-term increased morbidities. A high intake of carbohydrate during pregnancy combined with impaired glucose tolerance is postulated to result in high birth weight, which is linked to subsequent metabolic disease.

OBJECTIVE

The objective was to examine the association between carbohydrate intake in obese pregnant women and their offspring's body composition.

DESIGN

Secondary analyses were performed in an observational setting of 222 pregnant women with a pregestational BMI (in kg/m(2)) ≥30 participating in a randomized controlled trial. Diet was assessed at gestational weeks 11-14 and 36-37 by using a semiquantitative food-frequency questionnaire. Body composition in the offspring was assessed at birth by dual-energy X-ray absorptiometry. Relative fat mass (%) was the primary outcome. Absolute measures (total fat, abdominal fat, and lean body mass) were secondary outcomes.

RESULTS

Mean ± SD weight and absolute and relative fat mass in the offspring at birth were 3769 ± 542 g, 436 ± 214 g, and 11% ± 4%, respectively. Maternal intake of digestible carbohydrates was associated with the offspring's relative fat mass in late (P-trend = 0.006) but not early (P-trend = 0.15) pregnancy. A comparison of mothers in the highest (median: 238 g/d) compared with the lowest (median: 188 g/d) quartile of digestible carbohydrate intake showed a mean adjusted higher value in the offspring's relative fat mass of 2.1% (95% CI: 0.6%, 3.7%), which corresponded in absolute terms to a 103-g (95% CI: 27, 179-g) higher fat mass. Abdominal fat mass was also higher. In a strata of women with well-controlled glucose (2-h glucose values ≤6.6 mmol/L), no association between carbohydrate intake and offspring fat mass was observed, but the associations became significant and increased in strength with higher intolerance (strata with 2-h glucose values between 6.7-7.7 and ≥7.8 mmol/L).

CONCLUSION

In obese women, even those without gestational diabetes but with impaired glucose tolerance, a lower carbohydrate intake at moderate levels in late gestation is associated with a lower fat mass in their offspring at birth. The TOP study was registered at clinicaltrials.gov as NCT01345149.

Intake of Sweets, Snacks and Soft Drinks Predicts Weight Gain in Obese Pregnant Women: Detailed Analysis of the Results of a Randomised Controlled Trial

Background

Lifestyle interventions targeting obese pregnant women often result in modest reduction in gestational weight gain, pregnancy complications and related risk factors. Examining adherence to the intervention can, however, provide valuable information on the importance of the different factors targeted.

Objective

To evaluate improvements and relevance of different dietary factors targeted with respect to gestational weight gain in a 3-arm Randomised Controlled Trial (n=342) among obese pregnant women with BMI≥30 kg/m².

Methods

Randomisation 1:1:1 to either hypocaloric Mediterranean type of diet and physical activity intervention (D+PA); physical activity intervention alone (PA); or control (C). Diet was assessed at baseline (weeks 11–14) and endpoint (weeks 36–37) using a validated food frequency questionnaire.

Results

During the intervention women in the D+PA group significantly lowered their intakes of added sugars and saturated fat and increased their protein intake by ~1% of total energy compared to controls. Of these dietary variables only intakes of added sugar appeared to be related to GWG, while no association was observed for saturated fat or protein. Further analyses revealed that foods that contributed to intake of added sugars, including sweets, snacks, cakes, and soft drinks were strongly associated with weight gain, with women consuming sweets ≥2/day having 5.4 kg (95% CI 2.1-8.7) greater weight gain than those with a low (<1wk) intake. The results for soft drinks were more conflicting, as women with high weight gain tended to favour artificially sweetened soft drinks.

Conclusion

In our sample of obese pregnant women, craving for sweets, snacks, and soft drinks strongly predicts GWG. Emphasis on reducing intakes of these foods may be more relevant for limiting gestational weight gain than encouraging strict compliance to more specific diets.

Trial Registration

ClinicalTrials.gov NCT01345149

Diet or exercise, or both, for preventing excessive weight gain in pregnancy

BACKGROUND

This is an update of a Cochrane review first published in 2012, Issue 4. Excessive weight gain during pregnancy is associated with poor maternal and neonatal outcomes including gestational diabetes, hypertension, caesarean section, macrosomia, and stillbirth. Diet or exercise interventions, or both, may reduce excessive gestational weight gain (GWG) and associated poor outcomes; however, evidence from the original review was inconclusive.

OBJECTIVES

To evaluate the effectiveness of diet or exercise, or both, interventions for preventing excessive weight gain during pregnancy and associated pregnancy complications.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (5 November 2014), contacted investigators of the previously identified ongoing studies and scanned reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of diet or exercise, or both, interventions for preventing excessive weight gain in pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We organised RCTs according to the type of interventions and pooled data using the random-effects model in the Review Manager software. We also performed subgroup analyses according to the initial risk of adverse effects related to poor weight control. We performed sensitivity analysis to assess the robustness of the findings.

MAIN RESULTS

We included 65 RCTs, out of which 49 RCTs involving 11,444 women contributed data to quantitative meta-analysis. Twenty studies were at moderate-to-high risk of bias. Study interventions involved mainly diet only, exercise only, and combined diet and exercise interventions, usually compared with standard care. Study methods varied widely; therefore, we estimated the average effect across studies and performed sensitivity analysis, where appropriate, by excluding outliers and studies at high risk of bias.Diet or exercise, or both, interventions reduced the risk of excessive GWG on average by 20% overall (average risk ratio (RR) 0.80, 95% confidence interval (CI) 0.73 to 0.87; participants = 7096; studies = 24; I² = 52%). This estimate was robust to sensitivity analysis, which reduced heterogeneity, therefore we graded this evidence as high-quality. Interventions involving low glycaemic load diets, supervised or unsupervised exercise only, or diet and exercise combined all led to similar reductions in the number of women gaining excessive weight in pregnancy.Women receiving diet or exercise, or both interventions were more likely to experience low GWG than those in control groups (average RR 1.14, 95% CI 1.02 to 1.27; participants = 4422; studies = 11; I² = 3%; moderate-quality evidence). We found no difference between intervention and control groups with regard to pre-eclampsia (RR 0.95, 95% CI 0.77 to 1.16; participants = 5330; studies = 15; I² = 0%; high-quality evidence); however, maternal hypertension (not a pre-specified outcome) was reduced in the intervention group compared with the control group overall (average RR 0.70, 95% CI 0.51 to 0.96; participants = 5162; studies = 11; I² = 43%; low-quality evidence).There was no clear difference between groups with regard to caesarean delivery overall (RR 0.95, 95% CI 0.88 to 1.03; participants = 7534; studies = 28; I² = 9%; high-quality evidence); although the effect estimate suggested a small difference (5%) in favour of the interventions. In addition, for combined diet and exercise counselling interventions there was a 13% (-1% to 25%) reduction in this outcome (borderline statistical significance).We found no difference between groups with regard to preterm birth overall (average RR 0.91, 95% CI 0.68 to 1.22; participants = 5923; studies = 16; I² = 16%; moderate-quality evidence); however limited evidence suggested that these effect estimates may differ according to the types of interventions, with a trend towards an increased risk for exercise-only interventions.We found no clear difference between intervention and control groups with regard to infant macrosomia (average RR 0.93, 95% CI 0.86 to 1.02; participants = 8598; studies = 27; I² = 0%; high-quality evidence), although the effect estimate suggested a small difference (7% reduction) in favour of the intervention group. The largest effect size occurred in the supervised exercise-only intervention group (RR 0.81, 95% CI 0.64 to 1.02; participants = 2445; studies = 7; I² = 0%), which approached statistical significance (P = 0.07). Furthermore, in subgroup analysis by risk, high-risk women (overweight or obese women, or women with or at risk of gestational diabetes) receiving combined diet and exercise counselling interventions experienced a 15% reduced risk of infant macrosomia (average RR 0.85, 95% CI 0.73 to 1.00; participants = 3252; studies = nine; I² = 0; P = 0.05; moderate-quality evidence)There were no differences in the risk of poor neonatal outcomes including shoulder dystocia, neonatal hypoglycaemia, hyperbilirubinaemia, or birth trauma (all moderate-quality evidence) between intervention and control groups; however, infants of high-risk women had a reduced risk of respiratory distress syndrome if their mothers were in the intervention group (RR 0.47, 95% CI 0.26 to 0.85; participants = 2256; studies = two; I² = 0%; moderate-quality evidence).

AUTHORS' CONCLUSIONS

High-quality evidence indicates that diet or exercise, or both, during pregnancy can reduce the risk of excessive GWG. Other benefits may include a lower risk of caesarean delivery, macrosomia, and neonatal respiratory morbidity, particularly for high-risk women receiving combined diet and exercise interventions. Maternal hypertension may also be reduced. Exercise appears to be an important part of controlling weight gain in pregnancy and more research is needed to establish safe guidelines. Most included studies were carried out in developed countries and it is not clear whether these results are widely applicable to lower income settings.

Prevention of gestational diabetes in pregnant women with risk factors for gestational diabetes: a systematic review and meta-analysis of randomised trials

BACKGROUND

Gestational diabetes mellitus can be defined as 'glucose intolerance or hyperglycaemia with onset or first recognition during pregnancy.'

OBJECTIVE

The objective of our systematic review was to see if there was any intervention that could be used for primary prevention of gestational diabetes mellitus in women with risk factors for gestational diabetes mellitus.

SEARCH STRATEGY

Major databases were searched from 1966 to Aug 2012 without language restriction.

SELECTION CRITERIA

Randomised trials comparing intervention with standard care in women with risk factors for gestational diabetes were included. Meta-analysis was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. The primary outcome assessed was the incidence of gestational diabetes.

DATA COLLECTION AND ANALYSIS

Data from included trials were extracted independently by two authors and analysed using Rev-Man 5.

MAIN RESULTS

A total of 2422 women from 14 randomised trials were included; which compared diet (four randomised trials), exercise (three randomised trials), lifestyle changes (five randomised trials) and metformin (two randomised trials) with standard care in women with risk factors for gestational diabetes mellitus. Dietary intervention was associated with a statistically significantly lower incidence of gestational diabetes (Odds ratio 0.33, 95% CI 0.14 to 0.76) and gestational hypertension (Odds ratio 0.28, 95% CI 0.09, 0.86) compared to standard care. There was no statistically significant difference in the incidence of gestational diabetes mellitus or in the secondary outcomes with exercise, lifestyle changes or metformin use compared to standard care.

CONCLUSIONS

The use of dietary intervention has shown a statistically significantly lower incidence of gestational diabetes mellitus and gestational hypertension compared to standard care in women with risk factors for gestational diabetes mellitus.

Diet and exercise interventions for preventing gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a wide range of adverse health consequences for women and their babies in the short and long term. With an increasing prevalence of GDM worldwide, there is an urgent need to assess strategies for GDM prevention, such as combined diet and exercise interventions.

OBJECTIVES

To assess the effects of combined diet and exercise interventions for preventing GDM and associated adverse health consequences for women and their babies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (11 February 2014) and reference lists of retrieved studies. We updated the search in February 2015 but these results have not yet been incorporated and are awaiting classification.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and cluster-RCTs assessing the effects of interventions that included diet and exercise components. We included studies where combined diet and exercise interventions were compared with no intervention (i.e. standard care).We planned to also compare diet and exercise interventions with alternative diet and/or exercise interventions but no trials were identified for this comparison.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data and assessed the risk of bias of the included studies. Data were checked for accuracy.

MAIN RESULTS

We included 13 randomised controlled trials (involving 4983 women and their babies). We assessed the included trials as being of moderate risk of bias overall.When comparing women receiving a diet and exercise intervention with those receiving no intervention, there was no clear difference in the risk of developing GDM (average risk ratio (RR) 0.92, 95% confidence interval (CI) 0.68 to 1.23; 11 trials, 3744 women), caesarean section (RR 0.92, 95% CI 0.83 to 1.01; seven trials, 3246 women), or large-for-gestational age (RR 0.90, 95% CI 0.77 to 1.05; 2950 infants). Only one trial reported on perinatal mortality, and found no clear difference in the risk of stillbirth (RR 0.99, 95% CI 0.29 to 3.42; 2202 fetuses) or neonatal death (RR 0.99, 95% CI 0.06 to 15.85; 2202 neonates).Very few differences were shown between groups for the review's secondary outcomes, including for induction of labour, perineal trauma, pre-eclampsia, postpartum haemorrhage and infection, macrosomia, birthweight, small-for-gestational age, ponderal index, neonatal hypoglycaemia requiring treatment, hyperbilirubinaemia requiring treatment, shoulder dystocia, bone fracture or nerve palsy. Women receiving a combined diet and exercise intervention were, however, found to have a reduced risk of preterm birth compared with women receiving no intervention (RR 0.71, 95% CI 0.55 to 0.93; five trials, 2713 women).A trend towards reduced weight gain during pregnancy was shown for women receiving the combined diet and exercise intervention (mean difference (MD) -0.76 kg, 95% CI -1.55 to 0.03; eight trials, 2707 women; P = 0.06, random-effects); but no clear difference in postnatal weight retention was observed overall.In relation to adherence to the interventions, a number of trials that reported on behaviour modifications showed benefits in diet- (5/8 trials) and physical activity- (4/8 trials) related behaviours for women receiving the combined diet and exercise intervention, compared with women receiving no intervention; however there was notable variation across trials in outcomes measured and results observed. Only two trials reported on well-being and quality of life of women, and did not observe differences between groups for these outcomes.Very few trials reported on outcomes relating to the use of health services, although one trial suggested a reduced length of antenatal hospital stay for women receiving a combined diet and exercise intervention (MD -0.27 days, 95% CI -0.49 to -0.05; 2153 women).No information was available on outcomes for the infant as a child or adult, or for most longer-term outcomes for the mother.

AUTHORS' CONCLUSIONS

There are limitations associated with the available RCT evidence on the effects of combined diet and exercise interventions during pregnancy for preventing GDM. Results from 13 RCTs (of moderate quality) suggest no clear difference in the risk of developing GDM for women receiving a combined diet and exercise intervention compared with women receiving no intervention. However, the ability to draw firm conclusions was limited by variations in the quality of trials, characteristics of the interventions and populations assessed, and outcome definitions between trials.Based on the data currently available, conclusive evidence is not available to guide practice. Further large, well-designed RCTs, addressing the limitations of previous studies, are needed to assess the effects of combined interventions on preventing GDM and other relevant pregnancy outcomes including caesarean birth, large-for-gestational age and perinatal mortality. Health service utilisation and costs, and longer-term outcomes for mothers and their babies should be included. We identified another 16 trials which are ongoing and we will consider these for inclusion in the next update of this review.

Impact of maternal diet on neonatal anthropometry: a randomized controlled trial

OBJECTIVE

Large for gestational age infants are at increased risk of childhood obesity and maternal nutrition impacts birthweight. The aim of this study was to assess the impact of a maternal low glycaemic index (GI) diet on neonatal anthropometry.

METHODS

The ROLO (Randomised Control Trial of Low Glycaemic Index Diet in Pregnancy) study was a randomized controlled trial to assess the impact of a low GI diet versus usual diet on birthweight. It took place in a tertiary maternity hospital in Ireland and women were randomized to receive either a low GI diet or no dietary intervention from early pregnancy to term. Two hundred sixty-five neonates had anthropometric measurements on day 1-2 of life, 126 in the intervention group and 139 in the control group. Measurements included birthweight, length and circumferences of the head, chest, abdominal, thigh and mid-upper arm. A subgroup of 219 (82%) neonates also had skin-fold measurements.

RESULTS

Neonates whose mothers had a low GI diet in pregnancy had lower thigh circumference (15.9 ± 1.7 cm vs. 16.6 ± 1.5 cm, P = 0.04). There was no difference between the intervention and control groups in head, chest abdominal or mid-upper arm circumferences. No difference was noted between the two groups for any skin-fold measurements (subscapular, thigh, biceps and triceps).

CONCLUSION

Neonatal thigh circumference was altered by maternal low GI diet in pregnancy. These findings suggest that maternal low GI diet is safe in pregnancy and may positively impact infant adiposity.

Impact of maternal nutrition on pregnancy outcome--does it matter what pregnant women eat?

Pregnancy presents a unique époque in life with considerable potential to influence not only maternal health but also the health of the next generation. Nutritional interventions in pregnancy can influence maternal, foetal and infant health. This chapter describes the findings of a large randomised controlled trial on the impact of a low glycaemic index diet on maternal and foetal health and discusses areas of future research in this important area.

Maternal dietary glycemic index and glycemic load in early pregnancy are associated with offspring adiposity in childhood: the Southampton Women's Survey

BACKGROUND

Maternal hyperglycemia in pregnancy is associated with greater adiposity in offspring. The glycemic index (GI) and glycemic load (GL) describe the glycemic response to carbohydrate ingestion. However, the influence of maternal dietary GI and GL in pregnancy on childhood adiposity is unknown.

OBJECTIVE

We examined relations of maternal dietary GI and GL in early and late pregnancy with offspring body composition.

DESIGN

A total of 906 mother-child pairs from the prospective cohort the Southampton Women's Survey were included. Children underwent dual-energy X-ray absorptiometry measurements of body composition at birth and 4 and 6 y of age. Log-transformed fat mass and lean mass were standardized with a mean (±SD) of 0 ± 1. Maternal dietary GI and GL were assessed at 11 and 34 wk of gestation by using an administered food-frequency questionnaire.

RESULTS

After control for potential confounders, both maternal dietary GI and GL in early pregnancy were positively associated with fat mass at 4 and 6 y of age [fat mass SDs per 10-unit GI increase: β = 0.43 (95% CI: 0.06, 0.80), P = 0.02 at 4 y of age; β = 0.40 (95% CI: 0.10, 0.70), P = 0.01 at 6 y of age; fat mass SDs per 50-unit GL increase: β = 0.43 (95% CI: 0.19, 0.67), P < 0.001 at 4 y of age; β = 0.27 (95% CI: 0.07, 0.47), P = 0.007 at 6 y of age]. In contrast, there were no associations between maternal dietary GI or GL in late pregnancy and offspring fat mass at these ages. Maternal dietary GI and GL were not associated with fat mass at birth or offspring lean mass at any of the ages studied.

CONCLUSION

Higher maternal dietary GI and GL in early pregnancy are associated with greater adiposity in childhood.

Identification of those most likely to benefit from a low-glycaemic index dietary intervention in pregnancy

The present study is a secondary analysis of the ROLO study, a randomised control trial of a low-glycaemic index (GI) diet in pregnancy to prevent the recurrence of fetal macrosomia. The objectives of the present study were to identify which women are most likely to respond to a low-GI dietary intervention in pregnancy with respect to three outcome measures: birth weight; maternal glucose intolerance; gestational weight gain (GWG). In early pregnancy, 372 women had their mid-upper arm circumference recorded and BMI calculated. Concentrations of glucose, insulin and leptin were measured in early pregnancy and at 28 weeks. At delivery, infant birth weight was recorded and fetal glucose, C-peptide and leptin concentrations were measured in the cord blood. Women who benefited in terms of infant birth weight were shorter, with a lower education level. Those who maintained weight gain within the GWG guidelines were less overweight in both their first and second pregnancies, with no difference being observed in maternal height. Women who at 28 weeks of gestation developed glucose intolerance, despite the low-GI diet, had a higher BMI and higher glucose concentrations in early pregnancy with more insulin resistance. They also had significantly higher-interval pregnancy weight gain. For each analysis, women who responded to the intervention had lower leptin concentrations in early pregnancy than those who did not. These findings suggest that the maternal metabolic environment in early pregnancy is important in determining later risks of excessive weight gain and metabolic disturbance, whereas birth weight is mediated more by genetic factors. It highlights key areas, which warrant further interrogation before future pregnancy intervention studies, in particular, maternal education level and inter-pregnancy weight gain.

Seasonal variation in maternal and umbilical cord 25(OH) vitamin D and their associations with neonatal adiposity

DESIGN

Neonatal body fat is an important indicator of foetal energy supply and growth with potential importance for long-term health. In this study, we wanted to explore seasonal variation of 25-hydroxy-vitamin D (25(OH)D) in maternal and umbilical cord plasma (UCP) to examine whether maternal and foetal 25(OH)D levels were associated with maternal BMI and neonatal fat mass (FM), and to explore the relationship among maternal and neonatal 25(OH)D levels, maternal glucose/insulin levels and UCP C-peptide.

METHODS

An observational, prospective study of determinants of foetal growth and birth weight in healthy pregnant women. Total body composition in 202 newborns was measured by dual-energy X-ray absorptiometry. Circulating levels of biomarkers were assessed in mothers at gestational weeks 14-16 and 30-32 and UCP.

RESULTS

The mean 25(OH)D concentration in UCP was significantly lower than in maternal circulation (31 vs 45 nmol/l, P<0.001). Maternal and UCP 25(OH)D levels varied significantly with season. No significant association between maternal BMI (weeks 14-16) and UCP 25(OH)D concentration was found. We found a strong positive association between maternal 25(OH)D and UCP 25(OH)D (P<0.001). There was no significant linear association between maternal BMI (weeks 14-16) and maternal 25(OH)D. We found no association between maternal 25(OH)D levels and glucose/insulin levels, nor with maternal or UCP 25(OH)D on UCP C-peptide levels. Finally, neonatal total body FM was positively associated with UCP 25(OH)D, P=0.02.

CONCLUSIONS

We demonstrated seasonal variation in maternal and neonatal 25(OH)D levels at northern latitudes. UCP, but not maternal, 25(OH)D was a significant predictor of neonatal total FM. Maternal BMI and metabolic parameters such as glucose, insulin and UCP C-peptide levels were not associated with 25(OH)D in mothers or offspring.

Impact of a low glycemic index diet in pregnancy on markers of maternal and fetal metabolism and inflammation

This is a secondary analysis of 621 women in ROLO study, a randomized control trial of low glycemic index (GI) diet in pregnancy to prevent the recurrence of macrosomia, which aims to assess the effect of the diet on maternal and fetal insulin resistance, leptin, and markers of inflammation. In early pregnancy and at 28 weeks, serum was analyzed for insulin, leptin, tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6). At delivery, cord blood concentrations of leptin, TNF-α, IL-6, and C-peptide were recorded. We found no difference between those who did or did not receive low GI advice with respect to the concentrations of any marker in early pregnancy, at 28 weeks or in cord blood. Women in the intervention arm of the study did have a lower overall rise in insulin concentrations from early pregnancy to 28 weeks gestation, P = .04. Of the women in the intervention arm, 20% were in the highest quartile for insulin change (28-week insulin - insulin at booking) compared to 29% of controls (P = .02). In conclusion, a low GI diet in pregnancy has little effect on leptin and markers of inflammation although an attenuated response to the typical increase in insulin resistance seen in pregnancy with advancing gestation was seen in those who received the low GI advice.

Dietary glycemic index during pregnancy is associated with biomarkers of the metabolic syndrome in offspring at age 20 years

OBJECTIVE

Growing evidence indicates that metabolic syndrome is rooted in fetal life with a potential key role of nutrition during pregnancy. The objective of the study was to assess the possible associations between the dietary glycemic index (GI) and glycemic load (GL) during pregnancy and biomarkers of the metabolic syndrome in young adult offspring.

METHODS

Dietary GI and GL were assessed by questionnaires and interviews in gestation week 30 and offspring were clinically examined at the age of 20 years. Analyses based on 428 mother-offspring dyads were adjusted for maternal smoking during pregnancy, height, pre-pregnancy body mass index (BMI), education, energy intake, and the offspring's ambient level of physical activity. In addition, possible confounding by gestational diabetes mellitus was taken into account.

OUTCOME MEASURES

Waist circumference, blood pressure, HOMA insulin resistance (HOMA-IR) and plasma levels of fasting glucose, triglycerides, HDL cholesterol, LDL cholesterol, total cholesterol, insulin, and leptin were measured in the offspring.

RESULTS

Significant associations were found between dietary GI in pregnancy and HOMA-IR (the relative increase in HOMA-IR per 10 units' GI increase was 1.09 [95% CI: 1.01, 1.16], p = 0.02), insulin (1.09 [95% CI: 1.02, 1.16], p = 0.01) and leptin (1.21 [95% CI: 1.06, 1.38], p = 0.01) in the offspring; whereas no associations were detected for GL.

CONCLUSIONS

Our data suggests that high dietary GI in pregnancy may affect levels of markers for the metabolic syndrome in young adult offspring in a potentially harmful direction.