Dietary micronutrient intake during pregnancy is a function of carbohydrate quality

The ORIGINS Project: A Cross-Sectional Analysis of the Nutrition Profile of Pregnant Women in a Longitudinal Birth Cohort

Pregnancy is an opportunistic time for dietary intake to influence future disease susceptibility in offspring later in life. The ORIGINS Project was established to identify the factors that contribute to 'a healthy start to life' through a focus supporting childhood health and preventing disease (including non-communicable diseases). We aim to describe the dietary intakes of pregnant women in this cohort and to compare these to the Nutrient Reference Values (NRVs) and Australian Recommended Food Score (ARFS). The usual food and nutrient intakes of women were collected using the Australian Eating Survey (AES), a semi-quantitative food frequency questionnaire (FFQ). A total of 374 women completed the AES FFQ at both 20 weeks and 36 weeks of gestation between December 2016 and January 2023. Macronutrient, micronutrient, and food group intake were explored using descriptive statistics. Overall, it was found that the energy contribution from carbohydrates was low, while that from fat and saturated fat was high; participants were not meeting the recommendations for several key micronutrients (calcium, iron, iodine, and folate); and they had low diet quality scores for all food groups. These findings suggest that despite the ongoing promotion of healthy eating during pregnancy, further exploration into why dietary guidelines during pregnancy are not being adhered to is warranted.

Associations between Intake of Dietary Sugars and Diet Quality: A Systematic Review of Recent Literature

Understanding the relationship between the intake of sugars and diet quality can inform public health recommendations. This systematic review synthesized recent literature on associations between sugar intake and diet quality in generally healthy populations aged 2 years or older. We searched databases from 2010 to 2022 for studies of any design examining associations between quantified sugar intake in the daily diet and dietary indexes (DIs) or micronutrient intakes. Different sugar types and diet quality measures were analyzed separately. We converted DI results to Pearson's r correlations and grouped indexes with or without a free or added sugar component to facilitate cross-study comparisons. Meta-analysis was deemed inappropriate. From 13,869 screened records, we included 27 cross-sectional studies. NUQUEST risk of bias ratings were neutral (n = 18 studies) or poor (n = 9), and strength of evidence by the GRADE approach was very low due to study design. Most studies reported negative associations for added and free sugars with diet quality indexes (r ranging from -0.13 to -0.42) and nutrients of public health concern (fiber, vitamin D, calcium, potassium), while associations with total sugars were mixed. Due to cross-sectional study designs, the clinical relevance of these findings is unclear. Prospective studies are needed to minimize confounding and inform causal relationships.

Caloric and Lipid Profiles during Pregnancy in a Socio-Culturally Diverse Society

This research analyzes the determining factors in diet quality among the Spanish pregnant population with the aim of promoting healthier eating habits and preventing the development of non-communicable diseases. It is a diagnostic, non-experimental, cross-sectional, and observational study, with correlational descriptive methodology, and 306 participants. The information was collected using the 24 h dietary recall. Various sociodemographic factors that influence diet quality were analyzed. It was found that pregnant women consume too much protein and fat, score high in SFA consumption, and do not achieve the CH recommendations, consuming twice as much sugar. Carbohydrate intake is inversely related to income (β = -0.144, p < 0.005). Likewise, protein intake is linked to marital status (β = -0.114, p < 0.005) and religion (β = 0.110, p < 0.005). Finally, lipid intake appears conditional upon age (β = 0.109, p < 0.005). As regards the lipid profile, a positive association is only observed with age and MFA consumption (β = 0.161, p < 0.01). On the other hand, simple sugars are positively related to education (β = 0.106, p < 0.005). The results of this research show that the diet quality of pregnant women does not meet the nutritional recommendations established for the Spanish population.

Re-examination of the estimated average requirement for carbohydrate intake during pregnancy: Addition of placental glucose consumption

Evidence-based dietary reference intakes for nutrients in healthy individuals were last set in 2005 by the Institute of Medicine. For the first time, these recommendations included a guideline for carbohydrate intake during pregnancy. The recommended dietary allowance (RDA) was set at ≥175 g/d or 45%-65% of total energy intake. In the decades since, carbohydrate intake has been declining in some populations, and many pregnant women consume carbohydrates below the RDA. The RDA was developed to account for both maternal brain and fetal brain glucose requirements. However, the placenta also requires glucose as its dominant energy substrate and is as dependent on maternal glucose as the brain. Prompted by the availability of evidence demonstrating the rate and quantity of human placental glucose consumption, we calculated a potential new estimated average requirement (EAR) for carbohydrate intake to account for placental glucose consumption. Further, by narrative review, we have re-examined the original RDA by applying contemporary measurements of adult brain and whole-body fetal glucose consumption. We also propose, using physiologic rationale, that placental glucose consumption be included in pregnancy nutrition considerations. Calculated from human in vivo placental glucose consumption data, we suggest that 36 g/d represents an EAR for adequate glucose to support placental metabolism without supplementation by other fuels. A potential new EAR of 171 g/d accounts for maternal (100 g) and fetal (35 g) brain, and now placental glucose utilization (36 g), and with extrapolation to meet the needs of nearly all healthy pregnant women, would result in a modified RDA of 220 g/d. Lower and upper safety thresholds for carbohydrate intake remain to be determined, of importance as preexisting and gestational diabetes continue to rise globally, and nutrition therapy remains the cornerstone of treatment.

The Carbohydrate Threshold in Pregnancy and Gestational Diabetes: How Low Can We Go?

The original nutrition approach for the treatment of gestational diabetes mellitus (GDM) was to reduce total carbohydrate intake to 33-40% of total energy (EI) to decrease fetal overgrowth. Conversely, accumulating evidence suggests that higher carbohydrate intakes (60-70% EI, higher quality carbohydrates with low glycemic index/low added sugars) can control maternal glycemia. The Institute of Medicine (IOM) recommends ≥175 g/d of carbohydrate intake during pregnancy; however, many women are consuming lower carbohydrate (LC) diets (<175 g/d of carbohydrate or <40% of EI) within pregnancy and the periconceptual period aiming to improve glycemic control and pregnancy outcomes. This report systematically evaluates recent data (2018-2020) to identify the LC threshold in pregnancy in relation to safety considerations. Evidence from 11 reports suggests an optimal carbohydrate range of 47-70% EI supports normal fetal growth; higher than the conventionally recognized LC threshold. However, inadequate total maternal EI, which independently slows fetal growth was a frequent confounder across studies. Effects of a carbohydrate intake <175 g/d on maternal ketonemia and plasma triglyceride/free fatty acid concentrations remain unclear. A recent randomized controlled trial (RCT) suggests a higher risk for micronutrient deficiency with carbohydrate intake ≤165 g/d in GDM. Well-controlled prospective RCTs comparing LC (<165 g/d) and higher carbohydrate energy-balanced diets in pregnant women are clearly overdue.

Is a Higher Protein-Lower Glycemic Index Diet More Nutritious Than a Conventional Diet? A PREVIEW Sub-study

High protein diets and low glycemic index (GI) diets have been associated with improved diet quality. We compared the changes in nutrient intakes of individuals at high risk of developing type-2 diabetes over 3 y who followed either a higher protein-lower GI diet (HPLG) or a conventional moderate protein-moderate GI diet (MPMG). This post hoc analysis included 161 participants with overweight and pre-diabetes from the Australian cohort of the PREVIEW study (clinical trial registered in https://www.clinicaltrials.gov/ct2/show/NCT01777893?term=NCT01777893&draw=2&rank=1) who were randomly assigned to a HPLG diet (25% energy from protein, dietary GI ≤ 50, n = 85) or a MPMG diet (15% energy from protein, dietary GI ≥ 56, n = 76). Food records were collected at 0-mo (baseline) and at 6-, 12-, 24-, and 36-mo (dietary intervention period). Linear mixed models were used to compare the differences in total energy, macro- and micronutrients, dietary GI, glycemic load (GL) and body weight between the two diet groups at the 4 dietary intervention time points. At 3 y, 74% participants from the HPLG diet and 74% participants from the MPMG diet completed the trial. The HPLG group showed significantly higher protein intake and lower dietary GI and GL than the MPMG group (group fixed effect P < 0.001 for all three parameters). By 6-, 12-, 24-, and 36-mo there was a 3.0, 2.7, 2.2, and 1.4% point difference in protein intake and 6.2, 4.1, 4.8, and 3.9 GI unit difference between the groups. The intake of energy and saturated fat decreased (mostly in the first 6-mo), while the intake of dietary fiber increased (from mo-0 to mo-12 only) in both diets, with no significant differences between the diets. The dietary intakes of zinc (group fixed effect P = 0.05), selenium (P = 0.01), niacin (P = 0.01), vitamin B12 (P = 0.01) and dietary cholesterol (group by time fixed effect P = 0.001) were higher in the HPLG group than in the MPMG group. Despite both diets being designed to be nutritionally complete, a HPLG diet was found to be more nutritious in relation to some micronutrients, but not cholesterol, than a MPMG diet.

Examining the use of the FIGO Nutrition Checklist in routine antenatal practice: multistakeholder feedback to implementation

Objective

To gain insights from pregnant women and obstetricians on the utility of the FIGO Nutrition Checklist in antenatal practice.

Methods

Women were recruited from the antenatal department of a large tertiary‐level university maternity hospital in Dublin, Ireland, between October and December 2019. Participants completed the FIGO Nutrition Checklist before their routine antenatal appointment. Obstetricians and women were encouraged to discuss the FIGO Nutrition Checklist during the clinical visit. Completed FIGO Nutrition Checklists were collected after appointments. Acceptability was assessed through questionnaires.

Results

The majority (80.0%) of women answered “No” to at least one diet quality question, indicating a potential nutritional risk. While none of the participating obstetricians routinely discussed nutrition with women, all agreed that using the Checklist encouraged them to address nutrition with pregnant women. Nearly every woman (99.0%) found the Checklist quick to complete; however, all participating obstetricians felt there was not enough time to discuss it in routine practice. Despite this, most obstetricians and pregnant women recommended the FIGO Nutrition Checklist for use.

Conclusion

The FIGO Nutrition Checklist is acceptable for use in routine antenatal practice in tertiary care settings. It helped identify potentially at‐risk women during early pregnancy and facilitated conversations related to optimum diet.

The FIGO Nutrition Checklist is acceptable to pregnant women and may capture high‐risk weight or dietary practices in pregnancy that would otherwise go untreated.

Computer-based tailored dietary counselling improves the nutrient adequacy of the diet of French pregnant women: a randomised controlled trial

During pregnancy, mothers-to-be should adapt their diet to meet increases in nutrient requirements. Pregnant women appear to be keener to adopt healthier diets, but are not always successful. The objective of the present study was to determine whether a guided, stepwise and tailored dietary counselling programme, designed using an optimisation algorithm, could improve the nutrient adequacy of the diet of pregnant women, beyond generic guidelines. Pregnant women (n 80) who attended Notre-Dame-de-Bon-Secours Maternity Clinic were randomly allocated to the control or intervention arm. Dietary data were obtained twice from an online 3-d dietary record. The nutrient adequacy of the diet was calculated using the PANDiet score, a 100-point diet quality index adapted to the specific nutrient requirements for pregnancy. Women were supplied with generic dietary guidelines in a reference booklet. In the intervention arm, they also received nine sets of tailored dietary advice identified by an optimisation algorithm as best improving their PANDiet score. Pregnant women (n 78) completed the 12-week dietary follow-up. Initial PANDiet scores were similar in the control and intervention arms (60·4 (sd 7·3) v. 60·3 (sd 7·3), P = 0·92). The PANDiet score increased in the intervention arm (+3·6 (sd 9·3), P = 0·02) but not in the control arm (-0·3 (sd 7·3), P = 0·77), and these changes differed between arms (P = 0·04). In the intervention arm, there were improvements in the probabilities of adequacy for α-linolenic acid, thiamin, folate and cholesterol intakes (P < 0·05). Tailored dietary counselling using a computer-based algorithm is more effective than generic dietary counselling alone in improving the nutrient adequacy of the diet of French women in mid-pregnancy.

Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations

While dietary factors are important modifiable risk factors for type 2 diabetes (T2D), the causal role of carbohydrate quality in nutrition remains controversial. Dietary glycemic index (GI) and glycemic load (GL) have been examined in relation to the risk of T2D in multiple prospective cohort studies. Previous meta-analyses indicate significant relations but consideration of causality has been minimal. Here, the results of our recent meta-analyses of prospective cohort studies of 4 to 26-y follow-up are interpreted in the context of the nine Bradford-Hill criteria for causality, that is: (1) Strength of Association, (2) Consistency, (3) Specificity, (4) Temporality, (5) Biological Gradient, (6) Plausibility, (7) Experimental evidence, (8) Analogy, and (9) Coherence. These criteria necessitated referral to a body of literature wider than prospective cohort studies alone, especially in criteria 6 to 9. In this analysis, all nine of the Hill's criteria were met for GI and GL indicating that we can be confident of a role for GI and GL as causal factors contributing to incident T2D. In addition, neither dietary fiber nor cereal fiber nor wholegrain were found to be reliable or effective surrogate measures of GI or GL. Finally, our cost-benefit analysis suggests food and nutrition advice favors lower GI or GL and would produce significant potential cost savings in national healthcare budgets. The high confidence in causal associations for incident T2D is sufficient to consider inclusion of GI and GL in food and nutrient-based recommendations.

Global inequities in dietary calcium intake during pregnancy: a systematic review and meta-analysis

BACKGROUND

Evidence shows that adequate calcium intake during pregnancy reduces the risk of hypertensive disorders of pregnancy. In most low- and middle-income countries (LMICs) the daily calcium intake is well below recommendations. Mapping calcium intake during pregnancy worldwide and identifying populations with low calcium intake will provide the evidence base for more targeted actions to improve calcium intake.

OBJECTIVE

To assess dietary calcium intake during pregnancy worldwide.

SEARCH STRATEGY

MEDLINE and EMBASE (from July 2004 to November 2017).

SELECTION CRITERIA

Cross-sectional, cohort, and intervention studies reporting calcium intake during pregnancy.

DATA COLLECTION AND ANALYSIS

Five reviewers working in pairs independently performed screening, extraction, and quality assessment. We reported summary measures of calcium intake and calculated the weighted arithmetic mean for high-income countries (HICs) and LMICs independently, and for geographic regions, among studies reporting country of recruitment, mean intake, and total number of participants. When available, inadequate intakes were reported.

MAIN RESULTS

From 1880 citations 105 works met the inclusion criteria, providing data for 73 958 women in 37 countries. The mean calcium intake was 948.3 mg/day (95% CI 872.1-1024.4 mg/day) for HICs and 647.6 mg/day (95% CI 568.7-726.5 mg/day) for LMICs. Calcium intakes below 800 mg/day were reported in five (29%) countries from HICs and in 14 (82%) countries from LMICs.

CONCLUSION

These results are consistent with a lack of improvement in calcium dietary intake during pregnancy and confirm the gap between HICs and LMICs, with alarmingly low intakes recorded for pregnant women in LMICs. From the public health perspective, in the absence of specific local data, calcium supplementation of pregnant women in these countries should be universal.

TWEETABLE ABSTRACT

Despite dietary recommendations, women in LMICs face pregnancy with diets low in calcium.

Types of Carbohydrates Intake during Pregnancy and Frequency of a Small for Gestational Age Newborn: A Case-Control Study

The objective of this study was to assess the relationship between consumption of different types of carbohydrates (CHO) during pregnancy and the risk of having a small for gestational age (SGA) newborn. A retrospective matched case–control design was carried out with a total of 518 mother-offspring pairs. A total of 137 validated items were included in the food frequency questionnaire (FFQ). Conditional logistic regression models were used to calculate crude odds ratios (cORs) and adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Having more than 75 g/day of brown bread showed an inverse association with SGA (aOR = 0.64, CI 0.43–0.96). In contrast, an intake of industrial sweets more than once a day (aOR = 2.70, CI 1.42–5.13), or even 2–6 times a week (aOR = 1.84, CI 1.20–2.82), increased the odds of having a SGA newborn. During pregnancy, the higher the increase of wholegrain cereal and bread, the lower the possibility of having a SGA newborn, but the opposite occurred with refined sugar products—just consuming industrial bakery products or pastries twice a week increased the odds of having an SGA infant. Case–control studies cannot verify causality and only show associations, which may reflect residual confusion due to the presence of unknown factors. It is possible that a high consumption of sugary foods is a marker of a generally poor lifestyle.

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.

Multivitamin use and adverse birth outcomes in high-income countries: a systematic review and meta-analysis

BACKGROUND

In high-income countries, a healthy diet is widely accessible. However, a change toward a poor-quality diet with a low nutritional value in high-income countries has led to an inadequate vitamin intake during pregnancy.

OBJECTIVE

We conducted a systematic review and meta-analysis to evaluate the association between multivitamin use among women in high-income countries and the risk of adverse birth outcomes (preterm birth [primary outcome], low birthweight, small for gestational age, stillbirth, neonatal death, perinatal mortality, and congenital anomalies without further specification).

STUDY DESIGN

We searched electronic databases (MEDLINE, Embase, Cochrane, Scopus, and CINAHL) from inception to June 17, 2016, using synonyms of pregnancy, study/trial type, and multivitamins. Eligible studies were all studies in high-income countries investigating the association between multivitamin use (3 or more vitamins or minerals in tablets or capsules) and adverse birth outcomes. We evaluated randomized, controlled trials using the Cochrane Collaboration tool. Observational studies were evaluated using the Newcastle-Ottawa Scale. Meta-analyses were applied on raw data for outcomes with data for at least 2 studies and were conducted using RevMan (version 5.3). Outcomes were pooled using the random-effect model. The quality of evidence was assessed using the Grades of Research, Assessment, Development and Evaluation approach.

RESULTS

We identified 35 eligible studies including 98,926 women. None of the studies compared the use of folic acid and iron vs the use of multivitamins. The use of multivitamin did not change the risk of the primary outcome, preterm birth (relative risk, 0.84 [95% confidence interval, 0.69-1.03]). However, the risk of small for gestational age (relative risk, 0.77 [95% confidence interval, 0.63-0.93]), neural tube defects (relative risk, 0.67 [95% confidence interval, 0.52-0.87]), cardiovascular defects (relative risk, 0.83 [95% confidence interval, 0.70-0.98]), urine tract defects (relative risk, 0.60 [95% confidence interval, 0.46-0.78]), and limb deficiencies (relative risk, 0.68 [95% confidence interval, 0.52-0.89]) was decreased. Of the 35 identified studies, only 4 were randomized, controlled trials. The degree of clinical evidence according to the Grades of Research, Assessment, Development, and Evaluation system was low or very low for all outcomes except for recurrence of neural tube defects in which a moderate degree of clinical evidence was found.

CONCLUSION

Routine multivitamin use in high-income countries can be recommended but with caution because of the low quality of evidence. Randomized, controlled trials or well-performed, large prospective cohort studies are needed.

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.

Dietary glycaemic index and glycaemic load among Australian children and adolescents: results from the 2011–2012 Australian Health Survey

This study aimed to examine the dietary glycaemic index (GI) and glycaemic load (GL) of Australian children and adolescents, as well as the major food groups contributing to GL, in the recent 2011–2012 Australian Health Survey. Plausible food intake data from 1876 children and adolescents (51 % boys), collected using a multiple-pass 24-h recall, were analysed. The GI of foods was assigned based on a step-wise published method using values from common GI databases. Descriptive statistics were calculated for dietary GI, GL and contribution to GL by food groups, stratified by age group and sex. Linear regression was used to test for trends across age groups for BMI, dietary GI and GL, and intakes of energy, nutrients and food groups. Pearson’s χ2 test was used to test for differences between age groups for categorical subject characteristic variables. Mean dietary GI and GL of participants were 55·5 (sd 5·3) and 137·4 (sd 50·8), respectively. The main contributors to dietary GL were starchy foods: breads, cereal-based dishes, breakfast cereals, flours, grains and potatoes accounted for 41 % of total GL. Sweetened beverages, fruit and vegetable juices/drinks, cake-type desserts and sweet biscuits contributed 15 %. No significant difference (at P<0·001) was observed between sexes. In conclusion, Australian children and adolescents appear to consume diets with a lower GI than European children. Exchanging high-GI foods for low-GI alternatives within core and non-core foods may improve diet quality of Australian children and adolescents.