Fetal programming: the perspective of single and twin pregnancies

Association Between Maternal Body Mass Index and Fetal Acidosis in Term Twin Pregnancies: A Retrospective Cohort Study

OBJECTIVES

Given the increased risk of fetal acidosis in singleton neonates born to pregnant people with an elevated BMI, our objective was to evaluate the association between pre-pregnancy/first-trimester BMI and fetal acidosis among term twin pregnancies.

METHODS

Retrospective study of pregnant people with twin gestation and their term infants admitted to our centre between 2014 and 2019. Using a generalized estimating equation, the association between maternal BMI and fetal acidosis was determined using odds ratios (ORs) with 95% CIs. A two-sided P < 0.05 was considered significant.

RESULTS

A total of 275 pregnant people and 550 infants were analyzed. The number (%) of pregnancies in each BMI class were 10 (4%) underweight, 155 (56%) normal weight, 66 (24%) overweight, 22 (8%) class I, 9 (3%) class II, and 13 (5%) class III. The prevalence of maternal diabetes and hypertension was highest in class III (31%) and class II (44%), respectively. Fetal acidosis was diagnosed in 35 (6%) infants. After adjusting for confounders (maternal age, diabetes, and hypertension), infants born to those with elevated BMI did not have increased odds of fetal acidosis compared to those born to underweight and normal weight group (OR 1.29; 95% CI 0.38-4.41 for class I, P = 0.67 and OR 2.80; 95% CI 0.62-12.62 for the combined classes II and III, P = 0.18).

CONCLUSIONS

Maternal BMI was not associated with fetal acidosis in term twin pregnancies. Further research is required to corroborate study findings due to small sample size.

Singleton or twin male lambs: Effects on their reproductive development

Because intrauterine environment differs between twins and singletons, twin-born lambs are often studied when effects of fetal programming are evaluated. In sheep, fetal programming might have effects on reproductive physiology and behavior after sexual maturation. The aim of this study was to compare sperm output and sexual behavior in developing singleton- or twin-born lambs of similar body weight. Singleton lambs (n = 12) and twin (n = 9) male-male lambs were used. From 5.4 until 9.1 months of age, body weight, scrotal circumference (every 3-4 weeks), sexual behavior (every 14 days) and semen characteristics (every 28 days) were evaluated. In the third ejaculate, singleton lambs ejaculated a larger volume of semen than twins (P = 0.03). Considering a pool of the three ejaculates, twin lambs ejaculated semen with a greater sperm concentration than singleton lambs (P = 0.015). There was an interaction between group and time to the onset of courtship behavior (P = 0.02) and a tendency for an interaction in the number of mount attempts (P = 0.052). Singleton-born lambs, during the first evaluation period began courtship behavior earlier than twin-born lambs (P < 0.0001). In conclusion, there were only slight differences in semen and sexual behavior between male ram lambs born as singletons or twins with similar weight. Male ram lambs born as singletons initiated the courtship behavior earlier than twins during the first sexual behavioral evaluation period, ejaculated a larger volume of semen in the third consecutive ejaculate, and there was a lesser sperm concentration in the three ejaculates.

Placental restriction in multi-fetal pregnancies and between-twin differences in size at birth alter neonatal feeding behaviour in the sheep

Most individuals whose growth was restricted before birth undergo accelerated or catch-up neonatal growth. This is an independent risk factor for later metabolic disease, but the underlying mechanisms are poorly understood. This study aimed to test the hypothesis that natural and experimentally induced in utero growth restriction increase neonatal appetite and milk intake. Control (CON) and placentally restricted (PR) ewes carrying multiple fetuses delivered naturally at term. Outcomes were compared between CON (n=14) and PR (n=12) progeny and within twin lamb pairs. Lamb milk intake and feeding behaviour and ewe milk composition were determined using a modified weigh-suckle-weigh procedure on days 15 and 23. PR lambs tended to have lower birth weights than CON (−15%, P=0.052). Neonatal growth rates were similar in CON and PR, whilst heavier twins grew faster in absolute but not fractional terms than their co-twins. At day 23, milk protein content was higher in PR than CON ewes (P=0.038). At day 15, PR lambs had fewer suckling bouts than CON lambs and in females light twins had more suckling attempts than their heavier co-twins. Birth weight differences between twins positively predicted differences in milk intakes. Lactational constraint and natural prenatal growth restriction in twins may explain the similar milk intakes in CON and PR. Within twin comparisons support the hypothesis that prenatal constraint increases lamb appetite, although this did not increase milk intake. We suggest that future mechanistic studies of catch-up growth be performed in singletons and be powered to assess effects in each sex.

Maternal pre-gravid body mass index and obstetric outcomes in twin gestations

OBJECTIVE

The aim of this study is to evaluate the impact of maternal pre-gravid and/or first trimester overweight and obesity, and the adverse obstetrics outcome in twin pregnancies.

STUDY DESIGN

This is a retrospective study of women who delivered viable twins after 23 weeks of gestation with available prepregnancy body mass index (BMI) and/or were at their earliest visit during the first trimester of pregnancy in the period 2007-2011. The patients were divided into four subgroups according to their BMI (underweight, normal weight, overweight and obese) according to the WHO classification and their outcomes were compared. Obstetrical outcomes of interest including gestational diabetes, gestational hypertension, preterm birth, antepartum hemorrhage, intrahepatic cholestasis of pregnancy, method of delivery and neonatal intensive care unit (NICU) admission were all studied and compared.

RESULT

Electronic records of 1228 pregnant subjects who delivered twins were abstracted. Five hundred and four patients with twin gestations with available BMI were identified (underweight BMI<18.5% (n=22), normal weight BMI 18.5-24.9% (n=260), overweight 25-29.9% (n=114) and obese ⩾30% (n=108)). Obstetric complications occurred more often in the overweight and obese groups as compared with the normal weight group. There was an increased risk of gestational diabetes in overweight and obese women (odds ratio (OR), 3.3; 95% confidence interval (CI) 1.52-7.3; P=0.001) and (OR, 3.2; 95% CI, 1.41-7.1; P=0.002), respectively. There was an increased risk of gestational hypertension in the obese group compared with the normal weight group (OR, 2.29; 95% CI, 1.1-4.7; P=0.02) but not in the overweight group (OR, 1.71; 95% CI, 0.8-3.6; P=0.1). In addition, an increased risk of very preterm delivery (<32 weeks) in the overweight group and obese groups was seen when compared with the normal weight group (OR, 2.2; 95% CI, 1.18-4.20; P=0.014 and OR, 2; 95% CI, 1.024-3.91; P=0.04, respectively). Increased rate of cesarean section in the obese group was seen when compared with the normal weight group (OR, 2; 95% CI, 1.2-3.4; P=0.006). Risks of antepartum hemorrhage, intrahepatic cholestasis and NICU admission were similar between the groups.

CONCLUSION

In addition to the known obstetrics complications associated with twin gestations, the pregnancy outcomes in twins are further adversely influenced by increased maternal prepregnancy BMI.

Review: Placenta, evolution and lifelong health

The intrauterine environment has an important influence on lifelong health, and babies who grew poorly in the womb are more likely to develop chronic diseases in later life. Placental function is a major determinant of fetal growth and is therefore also a key influence on lifelong health. The capacity of the placenta to transport nutrients to the fetus and regulate fetal growth is determined by both maternal and fetal signals. The way in which the placenta responds to these signals will have been subject to evolutionary selective pressures. The responses selected are those which increase Darwinian fitness, i.e. reproductive success. This review asks whether in addition to responding to short-term signals, such as a rise in maternal nutrient levels, the placenta also responds to longer-term signals representing the mother's phenotype as a measure of environmental influences across her life course. Understanding how the placenta responds to maternal signals is therefore not only important for promoting optimal fetal growth but can also give insights into how human evolution affected developmental history with long-term effects on health and disease.

Report of the international symposium: polycystic ovary syndrome: first Latin-American consensus

During the last years, numerous consensuses have been held in different countries in order to review the data concerning diagnosis and treatment and their relationship with the ethnic origin, social status and lifestyle of women with Polycystic Ovary Syndrome (PCOS). This study describes the conclusions concerning diagnostic criteria and the appropriate treatment of women with PCOS reached during the International Symposium Polycystic Ovary Syndrome, First Latin-American Consensus held in Buenos Aires, Argentina on 4th and 5th May 2009 to be applied in South American.

Oxidative stress in twin neonates is influenced by birth weight and weight discordance

OBJECTIVES

To evaluate the extent of oxidative stress in neonates born from multiple gestation pregnancies who are at high risk of prematurity and growth abnormalities.

DESIGN AND METHODS

Blood samples were collected from umbilical cord of 72 twins, born at gestational age of 28-38 weeks, and 20 consecutive control singletons. Oxidative stress parameters (15-F(2t)-isoprostane, a marker of lipid peroxidation, and total antioxidant capacity, tAOC), were measured in cord plasma.

RESULTS

Levels of 15-F(2t)-isoprostane showed a moderate negative correlation with birth weight and were higher in small co-twins of discordant pairs; tAOC was positively correlated with birth weight but no significant difference was found between co-twins.

CONCLUSIONS

Oxidative stress levels in twins are mainly influenced by birth weight and weight discordance. We suggest that evaluation of cord blood 15-F(2t)-isoprostane might be of clinical value as maker of pre- and perinatal distress in twinning.

[Life course genetic epidemiologic study based on longitudinal twin-family data: a new perspective]

Family-based life course epidemiology is the approach to clarify long-term effects of accumulations and chains of biological and social risk exposures in one's life trajectory, namely, before and during conception, infancy, childhood, young adulthood and later adult life. Both genetic and environmental factors are considered. One of the theoretical rationales is the 'developmental origin of health and disease (DOHaD)' hypothesis. According to this theory, the causes of adult diseases are attributed to predictive adaptive responses and biological programming or epigenetic changes during a critical period of early life. If the environment later in life after birth is different from what is predicted, a mismatch has happened, leading to the development of a disease. This theory is supported by many epidemiologic studies, animal experiments, and evolution theory of biology. Longitudinal twin-family data are very powerful and useful information in the family-based life course genetic epidemiologic study.

Prepregnancy obesity and risk of stillbirth in viable twin gestations

We sought to estimate the impact of prepregnancy obesity on demise of one or both fetuses in twin gestations. We performed a retrospective cohort study using the Missouri maternally linked cohort files (years 1989-2005). Prepregnancy obesity was defined as a BMI >or=30. Outcomes of interest were stillbirth (intrauterine fetal death at >or=20 weeks' gestation) and demise of one (partial loss) or both (complete loss) fetuses, regardless of the cause. We used Cox Proportional Hazards with correction for intracluster correlation to obtain risk estimates. The overall stillbirth rate for twin gestations was 15.5/1,000 (18.4/1,000 vs. 14.5/1,000 in obese and normal weight mothers, respectively; P = 0.02). The rate for complete fetal loss was higher in obese mothers (8.3/1,000 vs. 5.6/1,000; P = 0.01) but was comparable for partial fetal loss (19.1/1,000 for obese vs. 16.3/1,000 for normal weight mothers; P = 0.1). Adjusted estimates confirmed these findings (adjusted hazards ratio (AHR) and 95% confidence interval (CI) = 1.31 (1.02-1.68) for stillbirth; AHR = 1.59; CI = 1.01-2.51) for complete loss; and AHR = 1.21; CI = 0.91-1.62) for partial loss. Subanalysis conducted on stillbirth showed that the risk associated with obesity was only elevated for same-sex (AHR = 1.54; CI = 1.15-2.04) but not opposite-sex twins (0.99; CI = 0.56-1.75). Our findings may find utility in counseling of obese women with twin gestations.

Gestational programming of offspring obesity/hypertension

The intrauterine milieu impacts fetal growth directly during gestation. It is now clear, however, that postnatal phenotype is also influenced by prenatal conditions. A variety of disorders in the adult have been linked to fetal size at birth; these include glucose intolerance, cardiovascular disease, and the subjects of this review, obesity and hypertension. We will review recent data regarding these associations and the pathophysiologic mechanisms underlying them in humans as well as in animal models.

Developmental programming and hypertension

PURPOSE OF REVIEW

There is a growing body of evidence linking adverse events or exposures during early life and adult-onset diseases. After important epidemiological studies from many parts of the world, research now focuses on mechanisms of organ dysfunction and on refining the understanding of the interaction between common elements of adverse perinatal conditions, such as nutrition, oxidants, and toxins exposures. This review will focus on advances in our comprehension of developmental programming of hypertension.

RECENT FINDINGS

Recent studies have unraveled important mechanisms of oligonephronia and impaired renal function, altered vascular function and structure as well as sympathetic regulation of the cardiovascular system. Furthermore, interactions between prenatal insults and postnatal conditions are the subject of intensive research. Prematurity vs. intrauterine growth restriction modulate differently programming of high blood pressure. Along with antenatal exposure to glucocorticoids and imbalanced nutrition, a critical role for perinatal oxidative stress is emerging.

SUMMARY

While the complexity of the interactions between antenatal and postnatal influences on adult blood pressure is increasingly recognized, the importance of postnatal life in (positively) modulating developmental programming offers the hope of a critical window of opportunity to reverse programming and prevent or reduce related adult-onset diseases.

Prenatal origins of adult disease

PURPOSE OF REVIEW

Human epidemiological and animal studies show that many chronic adult conditions have their antecedents in compromised fetal and early postnatal development. Developmental programming is defined as the response by the developing mammalian organism to a specific challenge during a critical time window that alters the trajectory of development with resulting persistent effects on phenotype. Mammals pass more biological milestones before birth than any other time in their lives. Each individual's phenotype is influenced by the developmental environment as much as their genes. A better understanding is required of gene-environment interactions leading to adult disease.

RECENT FINDINGS

During development, there are critical periods of vulnerability to suboptimal conditions when programming may permanently modify disease susceptibility. Programming involves structural changes in important organs; altered cell number, imbalance in distribution of different cell types within the organ, and altered blood supply or receptor numbers. Compensatory efforts by the fetus may carry a price. Effects of programming may pass across generations by mechanisms that do not necessarily involve structural gene changes. Programming often has different effects in males and females.

SUMMARY

Developmental programming shows that epigenetic factors play major roles in development of phenotype and predisposition to disease in later life.

The perinatal development of arterial pressure in sheep: effects of low birth weight due to twinning

The aim of this study is to determine the effect of fetal growth restriction due to twinning on the perinatal development of arterial pressure. Arterial pressure was recorded in fetal sheep (5 singletons, 8 twins) during late gestation and at 8 weeks after birth (11 singletons, 18 twins). In fetuses, there were no differences between singletons and twins in arterial pressure or plasma electrolytes. Postnatal twins were 17.3% lighter than singletons at birth, and growth rate was similar to singletons up to 8 weeks. After birth, arterial pressure was not different between groups, except that at 8 weeks, the systolic pressure was lower in twins. After birth, there were no differences between twins and singleton lambs in concentrations of plasma electrolytes, plasma renin, angiotensin II, and cortisol. Taken together with previous findings, the authors conclude that natural twinning in sheep followed by normal postnatal growth does not lead to hypertension.

Fetal origins of adult disease

The term 'fetal origins of adult disease' was coined on the basis of the inverse association between low birth weight and blood pressure, adult-onset diabetes, coronary heart disease, and stroke seen in numerous epidemiological studies. However, it seems unlikely that birth weight is involved in causal pathways underlying these observations, and if it were then the significance to public health of these findings is very limited because of our inability to modify birth weight to a relevant extent in humans. There has been a major focus on maternal nutrition. Despite evidence that experimental manipulation of maternal nutrition in animals influences offspring birth weight and programme measures related to cardiovascular disease, human studies in general provide limited and unconvincing evidence that differences in maternal macronutrient intake are important. Nevertheless there is a need to understand the underlying causal pathways, and the utility of studies of twins and possible mechanisms are discussed.

Adult hypertension and kidney disease: the role of fetal programming

Hypertension (HTN) and chronic kidney disease are highly prevalent diseases that tend to occur more frequently among disadvantaged populations, in whom prenatal care also tends to be poor. More and more evidence is emerging highlighting the important role of fetal programming in the development of adult disease, suggesting a possible common pathophysiologic denominator in the development of these disorders. Epidemiologic evidence accumulated over the past 2 decades has demonstrated an association between low birth weight and subsequent adult HTN, diabetes, and cardiovascular disease. More recently, a similar association has been found with chronic kidney disease. Animal studies and indirect evidence from human studies support the hypothesis that low birth weight, as a marker of adverse intrauterine circumstances, is associated with a congenital deficit in nephron number. The precise mechanism of the reduction in nephron number has not been established, but several hypotheses have been put forward, including changes in DNA methylation, increased apoptosis in the developing kidney, alterations in renal renin-angiotensin system activity, and increased fetal glucocorticoid exposure. A reduction in nephron number is associated with compensatory glomerular hypertrophy and an increased susceptibility to renal disease progression. HTN in low birth weight individuals also appears to be mediated in part through a reduction in nephron number. Increased awareness of the implications of low birth weight and inadequate prenatal care should lead to public health policies that may have long-term benefits in curbing the epidemics of HTN, diabetes, and kidney disease in generations to come.