Maternal Prepregnancy Weight and Congenital Heart Defects in the Offspring:

Systematic review and meta-analysis of prenatal risk factors for congenital heart disease: maternal chronic diseases and parental exposures

BACKGROUND

There is considerable heterogeneity in studies on prenatal risk factors for congenital heart diseases (CHDs). We performed a meta-analyse of all non-genetic factors of CHDs. This report presents results of factors related to maternal chronic diseases and parental exposures.

METHODS

A systematic search encompassing concepts of CHD and risk factors was used, using the following inclusion criteria: (1) original peer-reviewed articles, (2) quantifying the effects of risk factors for CHDs, (3) between 1989 and 2022. Pooled odds ratios (OR) and 95% confidence interval (CI) were calculated using a random effect model.

RESULTS

Inclusion criteria were met for 170 studies. There was an association between being overweight/obese and CHDs (OR 1.26; 95% CI 1.15-1.37), with a dose-effect relationship. Pregestational diabetes (PGDM) was associated with CHDs (OR 3.51; 95% CI 2.86-4.3), without difference between type I and type II PGDM. The effect size of gestational diabetes was less than that of PGDM (OR 1.38;95% CI: 1.18-1.61). There was an association between CHDs and preeclampsia (OR 2.01; 95% CI 1.32-3.05), and paternal smoking (OR 1.32; 95% CI 1.03-1.70) and alcohol use (OR 1.50; 95%CI 1.08-2.08). A smaller association was found with maternal smoking and advanced maternal age.

CONCLUSIONS

There exists robust evidence for increased risk of CHD in the presence of obesity, maternal diabetes, maternal smoking and increased maternal age. The effect sizes were relatively modest, except for PGDM. The robustness of the evidence decreased when CHDs were divided into subgroups, or when the analyses were restricted to severe CHDs.

Association of maternal physical and mental health characteristics with the hazard of having any medical condition or disability in Australian children: A 15-year birth cohort study

Any long-term medical condition or disability among children is a significant health issue. This study measured the incidence rate of any medical condition or disability among children from a nationally representative birth cohort, then used the random effect parametric survival regression model to assess whether the hazard of any medical condition or disability in children is associated with maternal physical and mental health characteristics (obesity, general health status, having a medical condition, stressful life events or mental illness). The study followed up 5019 children from the Longitudinal Study of Australian Children, assessing their time-to-event data from birth (2004) to 14 or 15 years of age (2018). The hazard rate of any medical condition or disability was 26.11 per 1000 person-years for all the children and 29.29 for the males-a noticeable gender difference. It was the highest (hazard rate: 62.90) among the children when their mothers had a medical condition, while the hazard rate was 22.40 per 1000 person-years among the children whose mothers had no medical conditions. The parametric panel regression results also suggested that the children of mothers with a medical condition during the 15-year study period were more likely to have a medical condition or disability (hazard ratio [HR]: 2.61, 95% confidence interval [CI]: 2.24-3.02) compared to the children of mothers with none. Similar trends were observed among children of mothers who had fair or poor general health (HR: 1.48, 95% CI: 1.15-1.91), obesity (HR: 1.40, 95% CI: 1.18-1.66) or experienced stressful life events (HR: 1.23, 95% CI: 1.06-1.43) over time compared to those whose mothers did not. These findings suggest that additional healthcare interventions targeting mothers with medical conditions, obesity, poor general health, or mental illness would help minimise the risk of medical conditions and disabilities among children.

Association Between Maternal Factors and Risk of Congenital Heart Disease in Offspring: A Systematic Review and Meta-Analysis

INTRODUCTION

This study aimed to summarize the evidence describing the relationship between maternal factors during gestation and risk of congenital heart disease (CHD) in offspring.

METHODS

PubMed, EMBASE, and the Cochrane Library were searched for potentially relevant reports from inception to May 2021. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) calculated by the random-effects model were used to evaluate the association between maternal factors and CHD risk.

RESULTS

There was a significant association between CHD risk and obesity in pregnancy (OR 1.29, 95% CI 1.22-1.37; P < 0.001), smoking in pregnancy (OR 1.16, 95% CI 1.07-1.25; P < 0.001), maternal diabetes (OR 2.65, 95% CI 2.20-3.19; P < 0.001), and exposure of pregnant women to organic solvents (OR 1.82, 95% CI 1.23-2.70; P = 0.003). No correlations were revealed between CHD susceptibility and advanced maternal age (OR 1.04, 95% CI 0.96-1.12; P = 0.328), underweight (OR 1.02, 95% CI 0.96-1.08; P = 0.519), alcohol intake in pregnancy (OR 1.08, 95% CI 0.95-1.22; P = 0.251), coffee intake (OR 1.18, 95% CI 0.97-1.44; P = 0.105), and exposure to irradiation (OR 1.80, 95% CI 0.85-3.80; P = 0.125).

DISCUSSION

Maternal factors including maternal obesity, smoking in pregnancy, maternal diabetes and exposure to organic solvents might predispose the offspring to CHD risk.

Maternal health and health-related behaviours and their associations with child health: Evidence from an Australian birth cohort

Objective

This study investigates the associations between maternal health and health-related behaviours (nutrition, physical activity, alcohol consumption and smoking) both during pregnancy and up to 15 months from childbirth and children’s health outcomes during infancy and adolescence (general health, presence of a chronic illness, and physical health outcome index).

Methods

This study used Wave 1 (2004) and Wave 7 (2016) data from the Longitudinal Survey of Australian Children (LSAC). We measured mothers’ general health, presence of a medical condition during pregnancy and mental health during pregnancy or in the year after childbirth. We subsequently measured the children’s general health, presence of a medical condition, and physical health outcome index at ages 0–1 (infancy) and 12–13 (adolescence). Binary logistic and linear regression analyses were performed to examine the association between the mothers’ health-related variables and their children’s health.

Results

Our results showed that poor general health of the mother in the year after childbirth was associated with higher odds of poor health in infants and adolescents in all three dimensions: poor general health (OR: 3.13, 95% CI: 2.16–4.52 for infants; OR: 1.39, 95% CI: 0.95–2.04 for adolescents), presence of a chronic condition (OR: 1.47, 95% CI: 1.19–1.81 for adolescents) and lower physical health score (b = −0.94, p-value <0.05 for adolescents). Our study also revealed that the presence of a chronic condition in mothers during pregnancy significantly increased the likelihood of the presence of a chronic condition in their offspring during infancy (OR: 1.31, 95% CI: 1.12–1.54) and during adolescence (OR: 1.45, 95% CI: 1.20–1.75). The study found that stressful life events faced by mothers increase the odds of poor general health or any chronic illness during adolescence, while stress, anxiety or depression during pregnancy and psychological distress in the year after childbirth increase the odds of any chronic illness during infancy.

Conclusions

The present study found evidence that poor maternal physical and mental health during pregnancy or up to 15 months from childbirth has adverse health consequences for their offspring as measured by general health, presence of chronic health conditions, and physical health index scores. This suggests that initiatives to improve maternal physical and mental health would not only improve child health but would also reduce the national health burden.

Maternal obesity and metabolic disorders associate with congenital heart defects in the offspring: A systematic review

BACKGROUND

Congenital heart defects (CHDs) are the most common congenital malformations. The aetiology of CHDs is complex. Large cohort studies and systematic reviews and meta-analyses based on these have reported an association between higher risk of CHDs in the offspring and individual maternal metabolic disorders such as obesity, diabetes, hypertension, and preeclampsia, all conditions that can be related to insulin resistance or hyperglycaemia. However, the clinical reality is that these conditions often occur simultaneously. The aim of this review is, in consequence, both to evaluate the existing evidence on the association between maternal metabolic disorders, defined as obesity, diabetes, hypertension, preeclampsia, dyslipidaemia and CHDs in the offspring, as well as the significance of combinations, such as metabolic syndrome, as risk factors.

METHODS

A systematic literature search of papers published between January 1, 1990 and January 14, 2021 was conducted using PubMed and Embase. Studies were eligible if they were published in English and were case-control or cohort studies. The exposures of interest were maternal overweight or obesity, hypertension, preeclampsia, diabetes, dyslipidaemia, and/or metabolic syndrome, and the outcome of interest was CHDs in the offspring. Furthermore, the studies were included according to a quality assessment score.

RESULTS

Of the 2,250 identified studies, 32 qualified for inclusion. All but one study investigated only the individual metabolic disorders. Some disorders (obesity, gestational diabetes, and hypertension) increased risk of CHDs marginally whereas pre-gestational diabetes and early-onset preeclampsia were strongly associated with CHDs, without consistent differences between CHD subtypes. A single study suggested a possible additive effect of maternal obesity and gestational diabetes.

CONCLUSIONS

Future studies of the role of aberrations of the glucose-insulin homeostasis in the common aetiology and mechanisms of metabolic disorders, present during pregnancy, and their association, both as single conditions and-particularly-in combination, with CHDs are needed.

Parental non-hereditary teratogenic exposure factors on the occurrence of congenital heart disease in the offspring in the northeastern Sichuan, China

Nonhereditary factors play an important role in the occurrence of congenital heart disease (CHD). This study was to explore the possible parental nonhereditary exposure factors relevant to the occurrence of CHD in the northeastern Sichuan area. A total of 367 children with CHD and 367 children without congenital malformations aged 0 to 14 years old were recruited from the Affiliated Hospital of North Sichuan Medical College and Nanchong Central Hospital between March 2016 and November 2018. This study was designed as a case-control study with 1:1 frequency matching, in which the parents of cases and controls were interviewed with the same questionnaire according to the gestational age of the child, maternal age during pregnancy and the same maternal race/ethnicity. Then, 322 matched case-control pairs were analysed by SPSS 22. Thirty-one suspicious factors were entered into the binary logistic regression analysis after univariate regression analysis of 55 factors (alpha = 0.05). The analysis results showed that 7 factors were significantly associated with the occurrence of CHD. Thus, augmenting maternal mental healthcare, improving the quality of drinking water, obtaining adequate nutrition, maintaining a healthy physical condition during pregnancy, enhancing parents’ level of knowledge and maintaining a healthy lifestyle may lower the occurrence of CHD.

Maternal Overweight and Obesity and Risk of Congenital Heart Defects

BACKGROUND

Congenital heart defects are more frequent in offspring of mothers with overweight or obesity. However, associations between maternal overweight and obesity, and risks of complex and specific heart defects are not clear.

OBJECTIVES

This study sought to analyze associations between maternal overweight and obesity severity and rates of complex and specific heart defects.

METHODS

This was a population-based cohort study in Sweden, including 2,050,491 live singleton infants born between 1992 and 2012. Data on maternal and infant characteristics, and diagnoses of congenital heart defects were retrieved from nationwide registries. Maternal body mass index (BMI) was categorized as underweight (BMI <18.5 kg/m²), normal weight (BMI 18.5 to <25 kg/m²), overweight (BMI 25 to <30 kg/m²), obesity class I (BMI 30 to <35 kg/m²), class II (BMI 35 to <40 kg/m²), and class III (BMI ≥40 kg/m²). Outcomes included complex heart defects (tetralogy of Fallot, transposition of the great arteries, atrial septal defects [ASD], aortic arch defects, and single-ventricle heart) and subgroups of specific heart defects diagnosed up to 5 years of age. The authors calculated adjusted prevalence rate ratios (PRRs) with 95% confidence intervals.

RESULTS

A total of 28,628 (1.40%, N = 2,050,491) children had at least 1 congenital heart defect. PRRs of aortic arch defects increased with maternal obesity severity. Compared with offspring of normal weight mothers, PRRs of aortic arch defects and transposition of the great arteries were doubled in offspring of mothers with severe obesity. PRRs of ASD and persistent ductus arteriosus in term infants increased with maternal BMI.

CONCLUSIONS

PRRs of aortic branch defects, ASD, and persistent ductus arteriosus increase with maternal obesity severity.

Tet inactivation disrupts YY1 binding and long-range chromatin interactions during embryonic heart development

Tet-mediated DNA demethylation plays an important role in shaping the epigenetic landscape and chromatin accessibility to control gene expression. While several studies demonstrated pivotal roles of Tet in regulating embryonic development, little is known about their functions in heart development. Here we analyze DNA methylation and hydroxymethylation dynamics during early cardiac development in both human and mice. We find that cardiac-specific deletion of Tet2 and Tet3 in mice (Tet2/3-DKO) leads to ventricular non-compaction cardiomyopathy (NCC) with embryonic lethality. Single-cell RNA-seq analyses reveal a reduction in cardiomyocyte numbers and transcriptional reprogramming in cardiac tissues upon Tet2/3 depletion. Impaired DNA demethylation and reduced chromatin accessibility in Tet2/3-DKO mice further compromised Ying-yang1 (YY1) binding to its genomic targets, and perturbed high-order chromatin organization at key genes involved in heart development. Our studies provide evidence of the physiological role of Tet in regulating DNA methylation dynamics and chromatin organization during early heart development.

Tet-mediated DNA demethylation is intimately involved in reguatling embryonic development. Here the authors characterise DNA methylation and hydroxymethylation dynamics during early cardiac development in both human and mice and provide evidence that Tet-mediated DNA demethylation plays a role in regulating chromatin organization during early heart development.

Maternal Body Mass Index and Risk of Congenital Heart Defects in Infants: A Dose-Response Meta-Analysis

Objective

The exact shape of the dose-response relationship between maternal body mass index (BMI) and the risk of congenital heart defects (CHDs) in infants has not been clearly defined yet. This study aims to further clarify the relationship between maternal obesity and the risk of CHDs in infants by an overall and dose-response meta-analysis.

Methods

PubMed, Embase, and Web of Science databases were searched to identify all related studies. The studies were limited to human cohort or case-control studies in English language. Random-effect models and dose-response meta-analysis were used to synthesize the results. Heterogeneity, subgroup analysis, sensitivity analysis, and publication bias were also assessed.

Results

Nineteen studies with 2,416,546 participants were included in our meta-analysis. Compared with the mothers with normal weight, the pooled relative risks (RRs) of infants with CHDs were 1.08 (95% CI=1.03-1.13) in overweight and 1.23 (95% CI=1.17-1.29) in obese mothers. According to the findings from the linear meta-analysis, we observed an increased risk of infants with CHDs (RR=1.07, 95% CI=1.06-1.08) for each 5 kg/m² increase in maternal BMI. A nonlinear relationship between maternal BMI and risk of infants with CHDs was also found (p=0.012).

Conclusion

The results from our meta-analysis indicate that increased maternal BMI is related to increased risk of CHDs in infants.

The association of elevated maternal genetic risk scores for hypertension, type 2 diabetes and obesity and having a child with a congenital heart defect

Background

Maternal hypertension, type 2 diabetes (T2D) and obesity are associated with an increased risk of having offspring with conotruncal heart defects (CTDs). Prior studies have identified sets of single nucleotide polymorphisms (SNPs) that are associated with risk for each of these three adult phenotypes. We hypothesized that these same SNPs are associated with maternal risk of CTDs in offspring.

Methods and results

We evaluated the parents of children with a CTD ascertained from the Children’s Hospital of Philadelphia (n = 466) and by the Pediatric Cardiac Genomic Consortium (n = 255). We used a family-based design to assess the association between CTDs and the maternal genotype for individual hypertension, T2D, and obesity-related SNPs and found no association between CTDs and the maternal genotype for any individual SNP. In addition, we calculated genetic risk scores (GRS) for hypertension, T2D, and obesity using previously published GRS formulas. When comparing the GRS of mothers to fathers, there were no statistically significant differences in the mean for the combined GRS or the GRS for each individual condition. However, when we categorized the mothers and fathers of cases with CTDs as having high (>95^th percentile) or low (≤95^th percentile) scores, compared to fathers, mothers had almost two times the odds of having a high GRS for hypertension (OR 1.7, 95% CI 1.0, 2.8) and T2D (OR 1.8, 95% CI 1.1, 3.1).

Conclusions

Our results support a link between maternal genetic risk for hypertension/T2D and CTDs in their offspring. These associations might be independent of maternal phenotype at conception.

Does Partial Meal Replacement During Pregnancy Reduce 12-Month Postpartum Weight Retention?

OBJECTIVE

This randomized trial tested whether a behavioral intervention with meal replacements in pregnancy could increase the proportion of women who returned to prepregnancy weight and reduce postpartum weight retention by 12 months after delivery.

METHODS

Women (N = 264; 13.7 weeks' gestation) with overweight or obesity were randomly assigned to usual care or intervention. The intervention reduced excess gestational weight gain and was discontinued at delivery. At follow-up, 83.7% completed the 12-month assessment.

RESULTS

Compared with usual care, prenatal intervention had no significant effect on odds of achieving prepregnancy weight (38/128 [29.7%] vs. 41/129 [31.8%]; P = 0.98) or in reducing the magnitude of weight retained (3.3 vs. 3.1 kg; P = 0.82) at 12 months. After delivery, significant (P < 0.0001) declines in meal replacements, practice of weight control behaviors, and dietary restraint were observed in the intervention group. Independent of group, lower gestational weight gain was the strongest predictor of achieving prepregnancy weight at 12 months (P = 0.0008).

CONCLUSIONS

A prenatal behavioral intervention with meal replacements that reduced pregnancy weight gain had no significant effect on 12-month postpartum weight retention.

Increased maternal Body Mass Index is associated with congenital heart defects: An updated meta-analysis of observational studies

PURPOSE

To review and summarize the epidemiologic evidence on the association of maternal Body Mass Index (BMI) with risk of congenital heart defects (CHDs) and to assess the possible dose-response patterns.

METHODS

Six electronic databases were searched for eligible studies up to April 2018. The summary risk estimates were calculated using either the fixed-effect models or random-effect models. A dose-response meta-analysis was also performed to capture the shape of the observed association. Subgroup and sensitivity analysis were conducted to explore the potential heterogeneity moderators.

RESULTS

Twenty-nine studies involving 99,205 CHDs cases among 6,467,422 participants were included in the meta-analysis. Mothers who were overweight (odds ratio [OR] = 1.07; 95% confidence intervals [CI]: 1.00-1.13) and obese (OR = 1.32; 95% CI: 1.21-1.43) had a significantly higher risk of total CHDs in their offspring when compared with those with normal weight. When obesity was further divided into class I (OR = 1.15; 95% CI: 1.11-1.20), class II (OR = 1.26; 95% CI: 1.18-1.34) and class III (OR = 1.42; 95% CI: 1.33-1.51) obesity, a significantly increased risk of total CHDs persisted. Different risks for specific CHD phenotypes were also found in different BMI categories. Furthermore, a nonlinear dose-response relationship between maternal BMI and risk of total CHDs was observed. Subgroup and sensitivity analyses identified the most relevant heterogeneity moderators.

CONCLUSION

The increased maternal BMI is associated with the risk of developing CHDs in offspring. Severe obesity can play an independent role in the observed association, but the effect may be mediated by diabetes mellitus. Preventing obesity or excessive weight gain is a priority for CHDs prevention.

Recent Advances in Placenta-Heart Interactions

Congenital heart defects (CHD) occur in ∼1 in every 100 live births. In addition, an estimated 10% of fetal loss is due to severe forms of CHD. This makes heart defects the most frequently occurring birth defect and single cause of in utero fatality in humans. There is considerable evidence that CHD is heritable, indicating a strong contribution from genetic risk factors. There are also known external environmental exposures that are significantly associated with risk for CHD. Hence, the majority of CHD cases have long been considered to be multifactorial, or generally caused by the confluence of several risk factors potentially from genetic, epigenetic, and environmental sources. Consequently, a specific cause can be very difficult to ascertain, although patterns of associations are very important to prevention. While highly protective of the fetus, the in utero environment is not immune to insult. As the conduit between the mother and fetus, the placenta plays an essential role in maintaining fetal health. Since it is not a fully-formed organ at the onset of pregnancy, the development of the placenta must keep pace with the growth of the fetus in order to fulfill its critical role during pregnancy. In fact, the placenta and the fetal heart actually develop in parallel, a phenomenon known as the placenta–heart axis. This leaves the developing heart particularly vulnerable to early placental insufficiency. Both organs share several developmental pathways, so they also share a common vulnerability to genetic defects. In this article we explore the coordinated development of the placenta and fetal heart and the implications for placental involvement in the etiology and pathogenesis of CHD.

Association between maternal body mass index and congenital heart defects in infants: A meta-analysis

We conducted this meta-analysis to address the open question of a possible association between maternal body mass index (BMI) and congenital heart defects (CHDs) in infants. We conducted a comprehensive computerized search of PubMed, Web of Science, Medline, and Embase databased (January 1980 through August 2017). We assessed the association between maternal BMI and the risk for congenital heart defects in their offspring. Study-specific relative risk estimates were polled according to random-effect or fixed-effect models. From 2567 citations, a total of 13 case-control studies and 4 cohort studies were selected for a meta-analysis, including more than 1 150 000 cases. The pooled odds radio (OR) of 1.065 (95% confidence interval [CI], 1.021-1.100; P = .001; I² = 60.1%) indicated a positive effect of maternal overweight status (BMI 25.0-29.9 kg/m² ) on the risk for congenital heart defects in infants. Moreover, we observed a significant association between maternal obesity (BMI ≥ 30 kg/m² ) and congenital heart defects in their offspring (OR: 1.174; 95% CI, 1.146-1.203, P = 0.161; I² =25.5%). However, there was little significant evidence of an association between maternal underweight status (BMI < 18.5 kg/m² ) and offspring with congenital heart defects, and the pooled OR was 1.015 (95% CI, 0.980-1.052; P = 0.085; I² =34.0%). Our meta-analysis provides robust evidence of the positive association between maternal BMI and the risk for fetal congenital heart defects.

Effect of Obesity on Gestational and Perinatal Outcomes

Purpose To assess the impact of pre-pregnancy obesity (body mass index [BMI] ≥ 30 kg/m2) on the gestational and perinatal outcomes. Methods Retrospective cohort study of 731 pregnant women with a BMI ≥ 30 kg/m2 at the first prenatal care visit, comparing them with 3,161 women with a BMI between 18.5 kg/m2 and 24.9 kg/m2. Maternal and neonatal variables were assessed. Statistical analyses reporting the demographic features of the pregnant women (obese and normal) were performed with descriptive statistics followed by two-sided independent Student's t tests for the continuous variables, and the chi-squared (χ2) test, or Fisher's exact test, for the categorical variables. We performed a multiple linear regression analysis of newborn body weight based on the mother's BMI, adjusted by maternal age, hyperglycemic disorders, hypertensive disorders, and cesarean deliveries to analyze the relationships among these variables. All analyses were performed with the R (R Foundation for Statistical Computing, Vienna, Austria) for Windows software, version 3.1.0. A value of p < 0.05 was considered statistically significant. Results Obesity was associated with older age [OR 9.8 (7.8-12.2); p < 0.01], hyperglycemic disorders [OR 6.5 (4.8-8.9); p < 0.01], hypertensive disorders [OR 7.6 (6.1-9.5); p < 0.01], caesarean deliveries [OR 2.5 (2.1-3.0); p < 0.01], fetal macrosomia [OR 2.9 (2.3-3.6); p < 0.01] and umbilical cord pH [OR 2.1 (1.4-2.9); p < 0.01). Conversely, no association was observed with the duration of labor, bleeding during labor, Apgar scores at 1 and 5 minutes after birth, gestational age, stillbirth and early neonatal mortality, congenital malformations, and maternal and fetal injury. Conclusion We observed that pre-pregnancy obesity was associated with maternal age, hyperglycemic disorders, hypertension syndrome, cesarean deliveries, fetal macrosomia, and fetal acidosis.

Do toxic metals and trace elements have a role in the pathogenesis of conotruncal heart malformations?

OBJECTIVE

The aim of the present study was to determine the role of toxic elements and trace elements in the pathogenesis of conotruncal heart defects by measuring their concentrations in the first meconium specimens of the affected newborns.

METHODS

Concentrations of lead, cadmium, iron, zinc, and copper were measured in 1st-day meconium specimens that were collected from 60 newborns with conotruncal heart defects (Group I) and 72 healthy newborns (Group II).

RESULTS

The newborns with conotruncal defects and the healthy newborns had statistically similar demographic and clinical characteristics. When compared with healthy newborns, mean concentrations of lead, cadmium, iron, zinc, and copper were significantly higher in newborns with conotruncal heart defects (p=0.001 for each). In total, 51 newborns with conotruncal heart defects had normal karyotype. These newborns had significantly higher concentrations of lead, cadmium, iron, zinc, and copper when compared with healthy newborns. There were significant and positive correlations between the concentrations of lead and cadmium (r=0.618, p=0.001), lead and iron (r=0.368, p=0.001), lead and zinc (r=0.245, p=0.005), lead and copper (r=0.291, p=0.001), cadmium and iron (r=0.485, p=0.001), cadmium and zinc (r=0.386, p=0.001), and cadmium and copper (r=0.329, p=0.001).

CONCLUSION

Toxic metals and trace elements may disturb DNA repair mechanisms by impairing DNA methylation profiles, and thus have a role in the pathogenesis of conotruncal heart defects.

Prenatal cannabis exposure - The "first hit" to the endocannabinoid system

As more states and countries legalize medical and/or adult recreational marijuana use, the incidences of prenatal cannabis exposure (PCE) will likely increase. While young people increasingly view marijuana as innocuous, marijuana preparations have been growing in potency in recent years, potentially creating global clinical, public health, and workforce concerns. Unlike fetal alcohol spectrum disorder, there is no phenotypic syndrome associated with PCE. There is also no preponderance of evidence that PCE causes lifelong cognitive, behavioral, or functional abnormalities, and/or susceptibility to subsequent addiction. However, there is compelling circumstantial evidence, based on the principles of teratology and fetal malprogramming, suggesting that pregnant women should refrain from smoking marijuana. The usage of marijuana during pregnancy perturbs the fetal endogenous cannabinoid signaling system (ECSS), which is present and active from the early embryonic stage, modulating neurodevelopment and continuing this role into adulthood. The ECSS is present in virtually every brain structure and organ system, and there is also evidence that this system is important in the regulation of cardiovascular processes. Endocannabinoids (eCBs) undergird a broad spectrum of processes, including the early stages of fetal neurodevelopment and uterine implantation. Delta-9-tetrahydrocannabinol (THC), the psychoactive chemical in cannabis, enters maternal circulation, and readily crosses the placental membrane. THC binds to CB receptors of the fetal ECSS, altering neurodevelopment and possibly rewiring ECSS circuitry. In this review, we discuss the Double-Hit Hypothesis as it relates to PCE. We contend that PCE, similar to a neurodevelopmental teratogen, delivers the first hit to the ECSS, which is compromised in such a way that a second hit (i.e., postnatal stressors) will precipitate the emergence of a specific phenotype. In summary, we conclude that perturbations of the intrauterine milieu via the introduction of exogenous CBs alter the fetal ECSS, predisposing the offspring to abnormalities in cognition and altered emotionality. Based on recent experimental evidence that we will review here, we argue that young women who become pregnant should immediately take a "pregnant pause" from using marijuana.

Antepartum Care of the Obese Patient

In the United States, roughly half of women are either overweight (24.5%) or obese (21.4%) when they become pregnant. Women who are obese before pregnancy are at increased risk for a number of pregnancy complications relative to normal-weight women. Specifically, obesity is associated with significantly increased maternal risks, including gestational diabetes mellitus, hypertensive disorders of pregnancy, and sleep disordered breathing. Maternal obesity is also associated with increased risks of adverse fetal outcomes, including prematurity, stillbirth, congenital anomalies, and abnormal fetal growth. In this review, we will discuss the implications of obesity with respect to antepartum care.

Periconceptional changes in weight and risk of delivering offspring with conotruncal heart defects

BACKGROUND

Maternal nutritional status has been recognized as a contributor to conotruncal heart defects, but there is limited understanding of the specific nutrition-related factors involved. In this California case-control study of 296 conotruncal cases and 695 nonmalformed controls we explored whether weight loss during early pregnancy was associated with an increased risk of d-transposition of the great arteries (dTGA) and tetralogy of Fallot (TOF) conotruncal defects.

METHODS

During telephone interviews women were asked whether they were dieting to lose weight or using weight loss remedies during 2 months before or 2 months after conception, and how much weight they gained or lost in the first 2 months of pregnancy or during the year before pregnancy.

RESULTS

Odds ratios for dieting to lose weight and use of weight loss remedies for dTGA and TOF were not substantially elevated and all had confidence intervals that included 1.0. Mothers who had a loss of >5 lbs in the first 2 months of pregnancy as well as mothers who lost and gained >5 lbs in the first 2 months of pregnancy also did not show a significant increased risk of delivering case infants when compared with women with no weight change in the year before pregnancy.

CONCLUSION

Given current recommendations about limited weight gain for obese pregnant women, these data indicate that dieting may not substantially increase a fetus' risk of having a conotruncal defect.

Obstructive heart defects associated with candidate genes, maternal obesity, and folic acid supplementation

Right-sided and left-sided obstructive heart defects (OHDs) are subtypes of congenital heart defects, in which the heart valves, arteries, or veins are abnormally narrow or blocked. Previous studies have suggested that the development of OHDs involved a complex interplay between genetic variants and maternal factors. Using the data from 569 OHD case families and 1,644 control families enrolled in the National Birth Defects Prevention Study (NBDPS) between 1997 and 2008, we conducted an analysis to investigate the genetic effects of 877 single nucleotide polymorphisms (SNPs) in 60 candidate genes for association with the risk of OHDs, and their interactions with maternal use of folic acid supplements, and pre-pregnancy obesity. Applying log-linear models based on the hybrid design, we identified a SNP in methylenetetrahydrofolate reductase (MTHFR) gene (C677T polymorphism) with a main genetic effect on the occurrence of OHDs. In addition, multiple SNPs in betaine-homocysteine methyltransferase (BHMT and BHMT2) were also identified to be associated with the occurrence of OHDs through significant main infant genetic effects and interaction effects with maternal use of folic acid supplements. We also identified multiple SNPs in glutamate-cysteine ligase, catalytic subunit (GCLC) and DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) that were associated with elevated risk of OHDs among obese women. Our findings suggested that the risk of OHDs was closely related to a combined effect of variations in genes in the folate, homocysteine, or glutathione/transsulfuration pathways, maternal use of folic acid supplements and pre-pregnancy obesity.

Inflammation in maternal obesity and gestational diabetes mellitus

BACKGROUND

The prevalence of maternal obesity is rising rapidly worldwide and constitutes a major obstetric problem, increasing mortality and morbidity in both mother and offspring. Obese women are predisposed to pregnancy complications such as gestational diabetes mellitus (GDM), and children of obese mothers are more likely to develop cardiovascular and metabolic disease in later life. Maternal obesity and GDM may be associated with a state of chronic, low-grade inflammation termed "metainflammation", as opposed to an acute inflammatory response. This inflammatory environment may be one mechanism by which offspring of obese women are programmed to develop adult disorders.

METHODS

Herein we review the evidence that maternal obesity and GDM are associated with changes in the maternal, fetal and placental inflammatory profile.

RESULTS

Maternal inflammation in obesity and GDM may not always be associated with fetal inflammation.

CONCLUSION

We propose that the placenta 'senses' and adapts to the maternal inflammatory environment, and plays a central role as both a target and producer of inflammatory mediators. In this manner, maternal obesity and GDM may indirectly program the fetus for later disease by influencing placental function.

'Fit Moms/Mamás Activas' internet-based weight control program with group support to reduce postpartum weight retention in low-income women: study protocol for a randomized controlled trial

BACKGROUND

High postpartum weight retention is a strong independent risk factor for lifetime obesity, cardiovascular disease, and type 2 diabetes in women. Interventions to promote postpartum weight loss have met with some success but have been limited by high attrition. Internet-based treatment has the potential to overcome this barrier and reduce postpartum weight retention, but no study has evaluated the effects of an internet-based program to prevent high postpartum weight retention in women.

METHODS/DESIGN

Fit Moms/Mamás Activas targets recruitment of 12 Women, Infants and Children (WIC) Supplemental Nutrition Program clinics with a total of 408 adult (>18 years), postpartum (<1 year) women with 14.5 kg or more weight retention or a body mass index of 25.0 kg/m(2) or higher. Clinics are matched on size and randomly assigned within county to either a 12-month standard WIC intervention or to a 12-month WIC enhanced plus internet-based weight loss intervention. The intervention includes: monthly face-to-face group sessions; access to a website with weekly lessons, a web diary, instructional videos, and computer-tailored feedback; four weekly text messages; and brief reinforcement from WIC counselors. Participants are assessed at baseline, six months, and 12 months. The primary outcome is weight loss over six and 12 months; secondary outcomes include diet and physical activity behaviors, and psychosocial measures.

DISCUSSION

Fit Moms/Mamás Activas is the first study to empirically examine the effects of an internet-based treatment program, coupled with monthly group contact at the WIC program, designed to prevent sustained postpartum weight retention in low-income women at high risk for weight gain, obesity, and related comorbidities.

TRIAL REGISTRATION

This trial was registered with Clinicaltrials.gov (identifier: NCT01408147 ) on 29 July 2011.

Association between maternal body mass index and congenital heart defects in offspring: a systematic review

The aim of this study was to investigate the relationship between maternal body mass index and all congenital heart defects (CHDs) combined and 11 individual defects. PubMed, ELSEVIER ScienceDirect, and Springer Link (up to February 2013) were searched, and the reference list of retrieved articles was reviewed. Three authors independently extracted the data. The systematic review included 24 studies, 14 of which were included in a metaanalysis. Statistical software was used to perform all statistical analyses. Fixed-effects or random-effects model was used to pool the results of individual study (expressed as odds ratios [ORs] with 95% confidence intervals [CIs]). A dose-response effect was observed between overweight, moderate obesity, and severe obesity and a pregnancy with any CHD (the pooled ORs: OR, 1.08 [95% CI, 1.02-1.15]; OR, 1.15 [95% CI, 1.11-1.20]; and OR, 1.39 [95% CI, 1.31-1.47], respectively) as well as some individual defects such as hypoplastic left heart syndrome, pulmonary valve stenosis, and outflow tract defects. When we excluded mothers with diabetes mellitus, the pooled ORs for all CHDs combined were 1.12 (95% CI, 1.04-1.20) and 1.38 (95% CI, 1.20-1.59) for moderately obese and severely obese, respectively. The highest increased risk was severely obese mothers for tetralogy of Fallot (OR, 1.94; 95% CI, 1.49-2.51). Being underweight did not increase the risk of any of the aforementioned CHDs but did increase the risk of aortic valve stenosis (OR, 1.47; 95% CI, 1.01-2.15]). The results of our study showed that increasing maternal body mass index was associated with an increasing risk of CHDs; severe obesity was an even greater risk factor for the development of CHDs.

Sleep disturbance and cardiometabolic risk factors in early pregnancy: a preliminary study

BACKGROUND

Cardiometabolic (CM) risk factors are linked to increased morbidity. Disturbed sleep is associated with CM risk factors in late pregnancy, but little is known about sleep in early pregnancy and CM risk factors.

METHODS

Diary and actigraphy-assessed sleep information, as well as CM outcomes (blood pressure (BP) and body mass index (BMI)), were collected thrice from pregnant women (N=161) in early pregnancy: T1 (10-12 weeks), T2 (14-16 weeks) and T3 (18-20 weeks). The sleep variables evaluated included sleep onset latency (SOL), wake after sleep onset (WASO) and total sleep time (TST). Sleep variables were dichotomised using established clinical cut-offs.

RESULTS

BMI and BP significantly changed across time. Women with persistent SOL≥20 min had greater BMI than women without persistent SOL≥20 min prior to covariate adjustment at T1 and T2, but at T3 the BMI values converged. Similar results were observed for persistent WASO≥30 min. Persistently long WASO, as measured by actigraphy, was associated with elevated SBP, after controlling for covariates.

CONCLUSIONS

Consistent with anecdotal evidence, it appears as if a subset of women report substantial difficulty initiating and maintaining sleep during early pregnancy and this may augment the risk of higher BP and BMI. Understanding these relationships is important as CM risk factors are linked to maternal and infant morbidity. Assessing sleep in early pregnancy may bestow time necessary for appropriate intervention.

Nongenetic risk factors and congenital heart defects

Advances have been made in identifying genetic etiologies of congenital heart defects. Through this knowledge, preventive strategies have been designed and instituted, and prospective parents are counseled regarding their risk of having an affected child. Great strides have been made in genetic variant identification, and genetic susceptibility to environmental exposures has been hypothesized as an etiology for congenital heart defects. Unfortunately, similar advances in understanding have not been made regarding strategies to prevent nongenetic risk factors. Less information is available regarding the potential adverse effect of modifiable risk factors on the fetal heart. This review summarizes the available literature on these modifiable exposures that may alter the risk for congenital heart disease. Information regarding paternal characteristics and conditions, maternal therapeutic drug exposures, parental nontherapeutic drug exposures, and parental environmental exposures are presented. Factors are presented in terms of risk for congenital heart defects as a group. These factors also are broken down by specific defect type. Although additional investigations are needed in this area, many of the discussed risk factors present an opportunity for prevention of potential disease.

Association between maternal chronic conditions and congenital heart defects: a population-based cohort study

BACKGROUND

This study quantifies the association between maternal medical conditions/illnesses and congenital heart defects (CHDs) among infants.

METHODS AND RESULTS

We carried out a population-based study of all mother-infant pairs (n=2,278,838) in Canada (excluding Quebec) from 2002 to 2010 using data from the Canadian Institute for Health Information. CHDs among infants were classified phenotypically through a hierarchical grouping of International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada codes. Maternal conditions such as multifetal pregnancy, diabetes mellitus, hypertension, and congenital heart disease were defined by use of diagnosis codes. The association between maternal conditions and CHDs and its subtypes was modeled using logistic regression with adjustment for maternal age, parity, residence, and other factors. There were 26 488 infants diagnosed with CHDs at birth or at rehospitalization in infancy; the overall CHD prevalence was 116.2 per 10,000 live births, of which the severe CHD rate was 22.3 per 10,000. Risk factors for CHD included maternal age ≥40 years (adjusted odds ratio [aOR], 1.48; 95% confidence interval [CI], 1.39-1.58), multifetal pregnancy (aOR, 4.53; 95% CI, 4.28-4.80), diabetes mellitus (type 1: aOR, 4.65; 95% CI, 4.13-5.24; type 2: aOR, 4.12; 95% CI, 3.69-4.60), hypertension (aOR, 1.81; 95% CI, 1.61-2.03), thyroid disorders (aOR, 1.45; 95% CI, 1.26-1.67), congenital heart disease (aOR, 9.92; 95% CI, 8.36-11.8), systemic connective tissue disorders (aOR, 3.01; 95% CI, 2.23-4.06), and epilepsy and mood disorders (aOR, 1.41; 95% CI, 1.16-1.72). Specific CHD subtypes were associated with different maternal risk factors.

CONCLUSIONS

Several chronic maternal medical conditions, including diabetes mellitus, hypertension, connective tissue disorders, and congenital heart disease, confer an increased risk of CHD in the offspring.

Impact of prenatal risk factors on congenital heart disease in the current era

Background

The healthcare burden related to congenital heart disease (CHD) is increasing with improving survival. We assessed changing trends in prenatal risk factors for CHD in the current era in a Canadian cohort.

Methods and Results

CHD patients <18 years old (n=2339) and controls without structural heart disease (n=199) were prospectively enrolled in an Ontario province‐wide biobank registry from 2008–2011. Family history, frequency of extra‐cardiac anomalies (ECAs), and antenatal risk factors were assessed. Temporal trends were analyzed and associations with CHD were measured using linear and logistic regression. Family history of CHD and frequency of major ECAs was higher in cases versus controls (P<0.001). Despite an increase in genetic testing in the recent era, only 9.5% of cases with CHD had a confirmed genetic diagnosis. Yield of genetic testing (ie, frequency of abnormal results) was higher in familial and syndromic cases. There was an increase in parental age at conception, maternal prepregnancy body mass index, maternal urinary tract infections, type 1 diabetes, and exposure to nonfertility medications during pregnancy from 1990–2011. Later year of birth, family history of CHD, presence of major ECAs, maternal smoking during pregnancy, and maternal medication exposure were associated with increased odds of CHD (P<0.05 for all). Advanced parental age was associated with increased odds of CHD caused by genetic abnormalities.

Conclusions

The increase in prenatal risk factors for CHD highlights the need for more rigorous ascertainment of genetic and environmental factors including gene‐environment interactions that contribute to CHD.

Obesity and the risk and detection of fetal malformations

The incidence of obesity in pregnancy has increased over the past 2 decades, with nearly 50% of U.S. women aged 15-49 years classified as overweight or obese. Obesity (independent of diabetes) among gravidae poses unique risks that extend toward the fetus, with several large population-based analyses demonstrating independent increased risks for fetal malformations including neural tube defects, cardiac anomalies, and orofacial clefts, as well as stillbirth and macrosomia. Unfortunately, several lines of evidence also suggest that the quality of the prenatal fetal anatomic survey and certain aspects of prenatal diagnostic screening programs are significantly limited. The net effect is that among obese gravidae, the increased risk of fetal anomalies is further offset by a concomitant diminished ability to sonographically detect such malformations in the prenatal interval. The purpose of this summary review is to systematically examine the evidence suggesting an increased risk of fetal malformations in obese gravidae, the contributing role of diabetes, and the limitations of prenatal diagnostic and sonographic screening among this at-risk population.

Overweight and obesity knowledge prior to pregnancy: a survey study

Background

Overweight and obesity are associated with increased risk for pregnancy complications. Knowledge about increased risks in overweight and obese women could contribute to successful prevention strategies and the aim of this study is to assess current levels of knowledge in a pregnant population.

Methods

Cross sectional survey of 412 consecutive unselected women in early pregnancy in Brisbane, Australia: 255 public women attending their first antenatal clinic visit and 157 women at private maternal fetal medicine clinics undergoing a routine ultrasound evaluation prior to 20 weeks gestation. The cohort was stratified according to pre pregnancy BMI (< 25.0 or ≥ 25.0). The main outcome measure was knowledge regarding the risks of overweight and obesity in pregnancy.

Results

Over 75% of respondents identified that obese women have an increased risk of overall complications, including gestational diabetes and hypertensive disorders of pregnancy compared to women of normal weight. More than 60% of women asserted that obesity would increase the risk of caesarean section and less than half identified an increased risk of adverse neonatal outcomes. Women were less likely to know about neonatal complications (19.7% did not know about the effect of obesity on these) than maternal complications (7.4%). Knowledge was similar amongst women recruited at the public hospital and those recruited whilst attending for an ultrasound scan at a private clinic. For most areas they were also similar between women of lower and higher BMI, but women with BMI < 25.0 were less likely to know that obesity was associated with increased rate of Caesarean section than those with higher BMI (16.8% versus 4.5%, P < 0.001). Higher educational status was associated with more knowledge of the risks of overweight and obesity in pregnancy.

Conclusions

Many women correctly identify that overweight and obesity increases the overall risk of complications of pregnancy and childbirth. The increased risks of maternal complications associated with being obese are better known than the increased risk of neonatal complications. Maternal education status is a main determinant of the extent of knowledge and this should be considered when designing education campaigns.

Genetic basis of susceptibility to teratogen induced birth defects

Birth defects remain the leading cause of infant death in US. The field of teratology has been focused on the causes and underlying mechanisms of birth defects for decades, yet our understanding of these critical issues remain unacceptably vague. Conclusions from years of animal and human studies made it clear that the vast majority of birth defects have multifactorial origins, with contributions from environmental and genetic factors. The environment comprises not only of the physical, biological, and chemical external environment surrounding the pregnant woman, but it also includes the internal environment of the woman's body that interact with the developing embryo in a complex fashion. The importance of maternal and embryonic genetic factors consisting of countless genetic variants/mutations that exist within every individual contribute to birth defect susceptibility is only now being more fully appreciated. This great complexity of the genome and its diversity within individuals and populations seems to be the principal reason why the same teratogenic exposure can induce severe malformation in one embryo, while fail to do so to other exposed embryos. As the interaction between genetic and environmental factors has long been recognized as the first "Principle of Teratology" by Wilson and Warkany [1965. Teratology: Principles and techniques. Chicago: University of Chicago Press], it is only recently that the appropriate investigative tools have been developed with which to fully investigate this fundamental principle. The introduction of high throughput technologies like whole genome sequencing or genome-wide association studies are promising to deliver an enormous amount of new data that will shed light on the genomic factors that contribute susceptibility to environmental teratogens. In this review, we attempt to summarize the epidemiological and experimental literature concerning birth defects whose phenotypic expression can be clearly related to the interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. © 2011 Wiley-Liss, Inc.

Special populations critical care considerations of the morbidly obese pregnant patient

The critically ill pregnant patient poses a unique challenge to the clinician, requiring a thorough understanding of normal and abnormal maternal and fetal physiology associated with pregnancy. The morbidly obese patient presents even greater challenges to the clinician, and morbidity and mortality are proportionately increased. Because increased numbers of obese pregnant women are now admitted to intensive care units, practitioners must be aware of the physiology associated with both pregnancy and obesity. A multidisciplinary approach is imperative to prevent both maternal and fetal morbidity and mortality for these very complex patients, especially when they are admitted to the ICU with critical illness.

Maternal obesity and congenital heart defects: a population-based study

BACKGROUND

Obesity affects almost one-third of pregnant women and causes many complications, including neural tube defects. It is not clear whether the risk of congenital heart defects, the most common malformations, is also increased.

OBJECTIVE

This study was conducted to determine whether obesity is associated with an increased risk of congenital heart defects.

DESIGN

A population-based, nested, case-control study was conducted in infants born with congenital heart defects and unaffected controls from the cohort of all births (n = 1,536,828) between 1993 and 2003 in New York State, excluding New York City. The type of congenital heart defect, maternal body mass index (BMI; in kg/m(2)), and other risk factors were obtained from the Congenital Malformations Registry and vital records. Mothers of 7392 congenital heart defect cases and 56,304 unaffected controls were studied.

RESULTS

All obese women (BMI > or = 30) were significantly more likely than normal-weight women (BMI: 19-24.9) to have children with a congenital heart defect [odds ratio (OR): 1.15; 95% CI: 1.07, 1.23; P < 0.0001]. Overweight women were not at increased risk (OR: 1.00; 95% CI: 0.94, 1.06). The risk in morbidly obese women (BMI > or = 40) was higher (OR: 1.33; 95% CI: 1.15, 1.54; P = 0.0001) than that in obese women with a BMI of 30-39.9 (OR: 1.11; 95% CI: 1.04, 1.20; P = 0.004). There was a highly significant trend of increasing OR for congenital heart defects with increasing maternal obesity (P < 0.0001). The offspring of obese women had significantly higher ORs for atrial septal defects, hypoplastic left heart syndrome, aortic stenosis, pulmonic stenosis, and tetralogy of Fallot.

CONCLUSIONS

Obese, but not overweight, women are at significantly increased risk of bearing children with a range of congenital heart defects, and the risk increases with increasing BMI. Weight reduction as a way to reduce risk should be investigated.

Maternal obesity and morbid obesity: the risk for birth defects in the offspring

BACKGROUND

The objective of this study was to assess, in a large data set from Swedish Medical Health Registries, whether maternal obesity and maternal morbid obesity were associated with an increased risk for various structural birth defects.

METHODS

The study population consisted of 1,049,582 infants born in Sweden from January 1, 1995, through December 31, 2007, with known maternal weight and height data. Women were grouped in six categories of body mass index (BMI) according to World Health Organization classification. Infants with congenital birth defects were identified from three sources: the Swedish Medical Birth Registry, the Register of Birth Defects, and the National Patient Register. Maternal age, parity, smoking, and year of birth were thought to be potential confounders and were included as covariates in the adjusted odds ratio analyses.

RESULTS

Ten percent of the study population was obese. Morbid obesity (BMI > or = 40) occurred in 0.7%. The prevalence of congenital malformations was 4.7%, and the prevalence of relatively severe malformations was 3.2%. Maternal prepregnancy morbid obesity was associated with neural tube defects OR 4.08 (95% CI 1.87-7.75), cardiac defects OR 1.49 (95% CI 1.24-1.80), and orofacial clefts OR 1.90 (95% CI 1.27-2.86). Maternal obesity (BMI > or = 30) significantly increased the risk of hydrocephaly, anal atresia, hypospadias, cystic kidney, pes equinovarus, omphalocele, and diaphragmatic hernia.

CONCLUSION

The risk for a morbidly obese pregnant woman to have an infant with a congenital birth defect is small, but for society the association is important in the light of the ongoing obesity epidemic.

Fetal anomalies in obese women: the contribution of diabetes

OBJECTIVE

To examine temporal changes in maternal weight and the association with major structural anomalies and other factors, such as diabetes, in our primary obstetric population.

METHODS

We conducted a serial, cross-sectional study using a perinatal database to identify all women with singletons who delivered in our system from 1991 to 2004. Three 5-year time epochs were defined to compare patient cohorts. Maternal weight, body mass index (BMI), diabetes status, incidence of major anomalies, and demographic data were compared. Multiple logistic regression was performed to estimate factors contributing to anomaly rates.

RESULTS

A total of 41,902 pregnancies were included. In each time epoch, there was an increase in the mean maternal weight, the mean BMI, the proportion of women weighing in excess of 200 lb, the proportion with a BMI higher than 29, the prevalence of pregestational diabetes, and the prevalence of major anomalies (all P<.001). There was no significant independent association between maternal obesity and the presence of a major anomaly. In a multivariable logistic model, the major factor contributing to the increasing rate of congenital anomalies was the prevalence of pregestational diabetes (odds ratio 3.8, 95% confidence interval 2.1-6.6). The population-attributable risk of anomalies related to obesity increased from essentially 0% in 1991-1994 to 6.1% in 2000-2004, whereas that related to diabetes increased from 3.3% to 9.2% during the same time periods.

CONCLUSION

Although the prevalence of maternal obesity and anomaly have increased, maternal weight alone was not associated with an increase in congenital anomalies. Instead, diabetes was significantly associated with the increase in the rate of anomalies seen in our population. Identification of maternal weight as a risk factor in epidemiologic studies may be a surrogate for pregestational diabetes.

LEVEL OF EVIDENCE

II.

Association between prepregnancy body mass index and congenital heart defects

OBJECTIVE

The purpose of this study was to examine associations between prepregnancy body mass index (BMI) and congenital heart defects (CHDs).

STUDY DESIGN

These analyses included case infants with CHDs (n = 6440) and liveborn control infants without birth defects (n = 5673) enrolled in the National Birth Defects Prevention Study (1997-2004).

RESULTS

Adjusted odds ratios for all CHDs combined were 1.16 (95% confidence interval [CI], 1.05-1.29), 1.15 (95% CI, 1.00-1.32), and 1.31 (95% CI, 1.11-1.56) for overweight status, moderate obesity, and severe obesity, respectively. Phenotypes associated with elevated BMI (> or =25.0 kg/m(2)) were conotruncal defects (tetralogy of Fallot), total anomalous pulmonary venous return, hypoplastic left heart syndrome, right ventricular outflow tract (RVOT) defects (pulmonary valve stenosis), and septal defects (secundum atrial septal defect).

CONCLUSION

These results corroborated those of previous studies and suggested new associations between obesity and conotruncal defects and RVOT defects.

Importance of gene-environment interactions in the etiology of selected birth defects

It is generally understood that both genetic and environmental factors contribute to the highly complex etiology of structural birth defects, including neural tube defects, oral clefts and congenital heart defects, by disrupting highly regulated embryonic developmental processes. The intrauterine environment of the developing embryo/fetus is determined by maternal factors such as health/disease status, lifestyle, medication, exposure to environmental teratogens, as well as the maternal genotype. Certain genetic characteristics of the embryo/fetus also predispose it to developmental abnormalities. Epidemiologic and animal studies conducted over the last few decades have suggested that the interplay between genes and environmental factors underlies the etiological heterogeneity of these defects. It is now widely believed that the study of gene-environment interactions will lead to better understanding of the biological mechanisms and pathological processes that contribute to the development of complex birth defects. It is only through such an understanding that more efficient measures will be developed to prevent these severe, costly and often deadly defects. In this review, we attempt to summarize the complex clinical and experimental literature on current hypotheses of interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. These include maternal folate nutritional status, maternal diabetes/obesity-related conditions, and maternal exposure to selected medications and environmental contaminants. Our goal is to highlight the potential gene-environment interactions affecting early embryogenesis that deserve comprehensive study.

Fetal anatomic evaluation in the overweight and obese gravida

OBJECTIVES

To evaluate the rate of completion of anatomic surveys of fetuses in overweight and obese gravid patients as compared with normal controls.

METHODS

This was a retrospective review of anatomic ultrasound scans performed between 2004 and 2007. Women were stratified by prepregnancy body mass index (BMI) into normal weight (BMI, 18.5-24.9 kg/m(2)), overweight (BMI, 25.0-29.9 kg/m(2)) and obese Class I (BMI, 30.0-34.9 kg/m(2)), Class II (BMI, 35.0-39.9 kg/m(2)) and Class III (BMI >or= 40.0 kg/m(2)) groups. Rates of completion of basic and comprehensive scans, gestational age at completion and number of scans required were compared.

RESULTS

For the 7140 patients included, completion rates for both the basic (normal weight, n = 2253 (79%); overweight, n = 1771 (76%); obese Class I, n = 767 (72%), Class II, n = 323 (61%) and Class III, n = 171 (49%)) and comprehensive (normal weight, n = 1234 (43%); overweight, n = 930 (40%); obese Class I, n = 404 (38%), Class II, n = 215 (41%) and Class III, n = 108 (31%)) surveys decreased significantly with increasing BMI (P < 0.00001). For surveys completed, the mean number of scans required was significantly higher for obese patients (basic: normal weight 1.3 vs. obese Class III 1.9; comprehensive: normal weight 1.7 vs. obese Class III, 2.2)(P < 0.00001). The overall completion rate improved at each gestational week, but was best between 20 and 23 weeks for obese patients.

CONCLUSIONS

As maternal BMI increases, the rate of completion of anatomic surveys decreases and the number of scans required increases. Delaying the initial survey until 20 weeks' gestation may improve the capacity to complete the examination in a single visit. It should be noted that these results represent completion rates at a tertiary referral center, and therefore may not reflect community experience.

Fetal nuchal translucency thickness evaluation in the overweight and obese gravida

OBJECTIVE

To evaluate the time required and failure rate for completion of nuchal translucency thickness (NT) measurements with increased maternal body mass index (BMI).

METHODS

This was a retrospective review of ultrasound examinations for NT measurement in 11-14-week singleton pregnancies performed at a single site from 2004 to 2007. Women were stratified by prepregnancy BMI into normal weight (BMI, 18.5-24.9 kg/m(2)), overweight (BMI, 25.0-29.9 kg/m(2)) and obese Class I (BMI, 30.0-34.9 kg/m(2)), Class II (BMI, 35.0-39.9 kg/m(2)) and Class III (BMI >or= 40.0 kg/m(2)) groups. The failure rate, the time required for measurement, and the total study time in min were evaluated by BMI class for the first attempt and for all attempts at NT measurement.

RESULTS

A total of 2508 women underwent attempted NT screening with complete data available on 1678 women (1707 examinations). The failure rate for NT screening varied significantly according to BMI (P < 0.001). At the first attempt, the median time for NT measurement varied significantly according to BMI (normal weight group, 9.7 (interquartile range (IQR) 4.4, 19.0) min; overweight group, 8.8 (4.0, 19.8) min; obese Class I, 9.6 (4.8, 20.4) min; Class II, 14.1 (5.0, 28.2) min; Class III, 12.3 (4.6, 22.7) min; P < 0.01), as did the total study time (normal group, 16.4 (10.1, 26.6) min; overweight group, 15.7 (9.8, 25.0) min, Class I, 17.3 (10.3, 29.2) min; Class II, 23.0 (12.2, 36.1) min; Class III, 18.7 (11.0, 30.8) min; P = 0.002). For all attempts also, the median time for NT measurement varied significantly according to BMI (normal weight group, 9.7 (IQR 4.4, 19.0) min; overweight group, 8.8 (4.0, 19.9) min; obese Class I, 9.6 (4.8, 21.0) min; Class II, 14.1 (5.0, 28.7) min; Class III, 12.3 (4.6, 22.5) min; P < 0.01), as did the total study time (normal weight group, 16.4 (10.2, 26.7) min; overweight group, 15.7 (9.8, 25.1) min; Class I, 17.6 (10.4, 29.9) min; Class II, 23.2 (12.0, 37.5) min; Class III, 18.7 (11.9, 31.9) min; P < 0.001).

CONCLUSION

As maternal BMI increases, the time required to obtain NT measurements and the failure rate increase. Before the ultrasound examination, patients with a BMI over 30 should be counseled regarding the need for additional time and failure rates for first-trimester screening.

Obesity in pregnancy: pre-conceptional to postpartum consequences

OBJECTIVE

To review the effects of obesity on reproduction and pregnancy outcome.

METHODS

A search of the literature was performed using key word searching and citation snowballing to identify English language articles published between January 1, 2000, and December 31, 2006, on the subject of obesity and its effects on pregnancy. Once the articles were identified, a thorough review of all results was conducted. Results and conclusions were compiled and summarized.

RESULTS

Obesity during pregnancy was linked with maternal complications ranging from effects on fertility to effects on delivery and in the postpartum period, as well as many complications affecting the fetus and newborn. The maternal complications associated with obesity included increased risks of infertility, hypertensive disorders, gestational diabetes mellitus, and delivery by Caesarean section. Fetal complications included increased risks of macrosomia, intrauterine fetal death and stillbirth, and admission to the neonatal intensive care unit.

CONCLUSION

Obesity causes significant complications for the mother and fetus. Interventions directed towards weight loss and prevention of excessive weight gain must begin in the pre-conception period. Obstetrical care providers must counsel their obese patients regarding the risks and complications conferred by obesity and the importance of weight loss. Maternal and fetal surveillance may need to be heightened during pregnancy; a multidisciplinary approach is useful. Women need to be informed about both maternal and fetal complications and about the measures that are necessary to optimize outcome, but the most important measure is to address the issue of weight prior to pregnancy.

Prepregnant obesity and risks of selected birth defects in offspring

BACKGROUND

Prepregnant obesity has been shown to be related to several birth defects, most notably neural tube defects. We investigated the previously observed association between obesity and spina bifida and also possible associations between obesity and other birth defects.

RESULTS

We conducted a case-control study of fetuses and liveborn infants among California births, July 1999 and June 2004. Of those eligible, 80% of case mothers (n = 659) and 77% of control mothers (n = 700) were interviewed. Cases were 147 infants with anencephaly, 191 with spina bifida, 142 with d-transposition of great arteries, and 181 with tetralogy of Fallot. Maternal body mass index (BMI) was based on prepregnant weight and height.

RESULTS

The odds ratios of birth defects with obesity (BMI > or =30 relative to normal BMI) were 1.6 for anencephaly (95% confidence intervals = 1.0-2.6); 1.4 for spina bifida (0.8-2.2); 0.7 for d-transposition of great arteries (0.4-1.4); and 0.8 for tetralogy of Fallot (0.4-1.4). Modestly elevated odds ratios were observed with obesity among women who reported weight gain in their waist before pregnancy-for anencephaly, 2.4 (1.2-5.1) and for spina bifida, 1.8 (0.9-3.6).

CONCLUSION

These data do not fully support earlier findings with respect to the relationships of obesity with anencephaly and spina bifida.

Obesity and diabetes: A recipe for obstetric complications

The prevalence of obesity has been increasing worldwide and has reached epidemic proportions in the United States, where well over 20% of the population have a body mass index (BMI) within the obese range. Obesity is associated with a wide spectrum of obstetric and perinatal complications, including increased risks of fetal mortality and morbidity, congenital malformations, maternal hypertensive disorders, gestational diabetes, excessive fetal growth and cesarean delivery. The odds ratios for these risks increase in direct correlation with the severity of obesity, and are significant even among women who are overweight without meeting criteria for obesity. Although obesity is closely associated with diabetes which, in itself, is associated with similar perinatal complications, diabetes and obesity are independent risk factors for adverse pregnancy outcome. Moreover, improving glycemic control in the pregnant woman with diabetes may mitigate the additive adverse effects of diabetes and obesity on pregnancy outcome.