Association of Maternal Obesity With Longitudinal Ultrasonographic Measures of Fetal Growth: Findings From the NICHD Fetal Growth Studies-Singletons

Developmental Programming of Body Composition: Update on Evidence and Mechanisms

PURPOSE OF REVIEW

A growing body of epidemiological and experimental data indicate that nutritional or environmental stressors during early development can induce long-term adaptations that increase risk of obesity, diabetes, cardiovascular disease, and other chronic conditions-a phenomenon termed "developmental programming." A common phenotype in humans and animal models is altered body composition, with reduced muscle and bone mass, and increased fat mass. In this review, we summarize the recent literature linking prenatal factors to future body composition and explore contributing mechanisms.

RECENT FINDINGS

Many prenatal exposures, including intrauterine growth restriction, extremes of birth weight, maternal obesity, and maternal diabetes, are associated with increased fat mass, reduced muscle mass, and decreased bone density, with effects reported throughout infancy and childhood, and persisting into middle age. Mechanisms and mediators include maternal diet, breastmilk composition, metabolites, appetite regulation, genetic and epigenetic influences, stem cell commitment and function, and mitochondrial metabolism. Differences in body composition are a common phenotype following disruptions to the prenatal environment, and may contribute to developmental programming of obesity and diabetes risk.

In overweight and obese women, fetal ultrasound biometry accurately predicts newborn measures

INTRODUCTION

The aim of this study was to evaluate the association between fetal ultrasound and newborn biometry and adiposity measures in the setting of maternal obesity.

MATERIAL AND METHODS

The study population involved 845 overweight or obese pregnant women, who participated in the Standard Care Group of the LIMIT randomised trial (ACTRN12607000161426, 9/03/2007). At 36 weeks gestation, fetal biometry, estimated fetal weight (EFW) and adiposity measures including mid-thigh fat mass (MTFM), subscapular fat mass (SSFM), and abdominal fat mass (AFM) were undertaken using ultrasound. Neonatal anthropometric measurements obtained after birth included birthweight, head circumference (HC), abdominal circumference (AC) and skinfold thickness measurements (SFTM) of the subscapular region and abdomen.

RESULTS

At 36 weeks gestation, every 1 g increase in EFW was associated with a 0.94 g increase in birthweight (95% CI 0.88-0.99; P < 0.001). For every 1 mm increase in the fetal ultrasound measure, there was a 0.69 mm increase in birth HC (95% CI 0.63-0.75, P < 0.001) and 0.69 mm increase in birth AC (95% CI 0.60-0.79, P < 0.001). Subscapular fat mass in the fetus and the newborn (0.29 mm, 95% CI 0.20-0.39, P < 0.001) were moderately associated, but AFM measurements were not (0.06 mm, -0.03 to 0.15, P = 0.203). There is no evidence that these relationships differed by maternal body mass index.

CONCLUSION

In women who are overweight or obese, fetal ultrasound accurately predicts neonatal HC and AC along with birthweight.

Maternal adipokines longitudinally measured across pregnancy and their associations with neonatal size, length, and adiposity

BACKGROUND/OBJECTIVES

Maternal obesity impacts fetal growth as early as second trimester of pregnancy, yet little is known about the molecular mechanisms involved. We aimed to examine associations between maternal adipokines throughout pregnancy and neonatal size by prepregnancy obesity status.

METHODS

In a prospective cohort of 2802 U.S. pregnant women from the NICHD Fetal Growth Studies-Singleton Cohort (2009-2013), biospecimens were analyzed in a matched case-control subset of 321 women. Blood was collected at 10-14, 15-26 (fasting), 23-31, and 33-39 gestational weeks. Plasma leptin and soluble leptin receptor (sOB-R) and total and high-molecular-weight (HMW)-adiponectin were measured. Free leptin was calculated as leptin/sOB-R. Birthweight was abstracted from medical records. Neonatal length and skinfolds were measured.

RESULTS

Leptin and sOB-R in late pregnancy tended to be positively and negatively associated with neonatal length, respectively, while free leptin throughout pregnancy tended to be positively associated with length. Free leptin associations with neonatal length were differential by obesity (i.e., inversely among women without obesity and positively among women with obesity). A per unit increase in free leptin at 33-39 weeks was associated with a shorter neonatal length by -0.55 cm (95%CI, -0.83, -0.28) in women without obesity and longer length by 0.49 cm (95%CI, 0.34, 0.65) in women with obesity. HMW-adiponectin at 33-39 weeks was inversely associated with neonatal length (β = -1.29 cm; 95%CI, -1.74, -0.85) and skinfold thickness (β = -1.46 mm; 95%CI, -1.58, -0.56) among women with obesity. Free leptin across pregnancy tended to be negatively associated with neonatal skinfold thickness among women without obesity, while free leptin in early pregnancy was positively associated with skinfold thickness.

CONCLUSIONS

Maternal adipokines were associated with multiple pathways that influence neonatal size including length and adiposity, which differed in timing across pregnancy and by prepregnancy obesity. These findings provide new potential insights into mechanisms and timing by which maternal obesity may impact fetal growth.

Associations of Pre-Pregnancy BMI, Gestational Weight Gain and Maternal Parity with the Trajectory of Weight in Early Childhood: A Prospective Cohort Study

Background: The association of maternal parity, pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with childhood weight status has been well studied; however, little is known about these factors with respect to the rate of weight changes in early childhood. Methods: This study was based on a prospective longitudinal study. The follow-up surveys were conducted at the ages of 1, 3, 6, 8, 12, and 18 months. Child weight was investigated twice at each wave. Data on maternal parity, pre-pregnancy weight and height were collected at baseline. The latent growth curve model was used to examine the effects of interested predictors on the trajectory of weight in early childhood. Results: Finally, 893 eligible mother-child pairs were drawn from the cohort. In adjusted models, multiparas were associated with higher birth weight (β = 0.103) and slower weight change rate of children (β = −0.028). Pre-conception BMI (β = 0.034) and GWG (β = 0.014) played important roles in the initial status of child weight but did not have effects on the rate of weight changes of the child. Conclusions: Multiparous pregnancy is associated with both higher mean birth weight and slower weight-growth velocity in early childhood, while pregravid maternal BMI and GWG are only related to the birth weight.

The effect of maternal obesity on fetal biometry, body composition, and growth velocity

Introduction: The aim of this secondary analysis was to investigate the relationship between maternal body mass index (BMI) and fetal biometry, body composition, and velocity measurements at 28 and 36 weeks gestation.Materials and methods: The current analysis involves 911 overweight or obese women who were randomized to the Standard Care group of the LIMIT randomized trial.Results: The fetus of women with Class 3 obesity (BMI ≥ 40.0) showed the greatest increase in all biometry z-scores, abdominal area (AA), and abdominal fat mass (AFM) compared with women classified as overweight (BMI 25.0-29.9). In women with Class 3 obesity, AA velocity was increased by 0.035 cm² (0.004, 0.066, p = .029) and the z-score velocity was increased by 0.238 (0.022, 0.453, p = .03). Estimated fetal weight (EFW) velocity for women with Class 3 obesity was higher than that of overweight women by 2.028 g per day (0.861, 3.196, p<.001) and the z-score velocity was also higher by 0.441 per day (0.196, 0.687, p < .001).Conclusions: Maternal obesity is associated with an increase in fetal abdominal circumference, AFM and area along with EFW velocity over time. Women with Class 3 obesity (BMI ≥ 40.0) may represent a higher risk group for perpetuating the intergenerational transmission of obesity to their offspring.

Longitudinal Maternal Vitamin D Status during Pregnancy Is Associated with Neonatal Anthropometric Measures

Findings on maternal 25-hydroxyvitamin D (25[OH]D) and neonatal anthropometry are inconsistent, and may at least be partly due to variations in gestational week (GW) of 25(OH)D measurement and the lack of longitudinal 25(OH)D measurements across gestation. The aim of the current study was to examine the associations of longitudinal measures of maternal 25(OH)D and neonatal anthropometry at birth. This study included 321 mother–offspring pairs enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies–Singletons. This study was a prospective cohort design without supplementation and without data on dietary supplementation. Nevertheless, measurement of plasma 25(OH)D reflects vitamin D from different sources, including supplementation. Maternal concentrations of total 25(OH)D were measured at 10–14, 15–26, 23–31, and 33–39 GW and categorized as <50 nmol/L, 50–75 nmol/L, and >75 nmol/L. Generalized linear models were used to examine associations of 25(OH)D at each time-point with neonate birthweight z-score, length, and sum of skinfolds at birth. At 10–14 GW, 16.8% and 49.2% of women had 25(OH)D <50 nmol/L and between 50–75 nmol/L, respectively. The association of maternal 25(OH)D with neonatal anthropometry differed by GW and women’s prepregnancy BMI (normal (<25.0 kg/m²), overweight/obese (25.0–44.9 kg/m²)). All analyses were stratified by prepregnancy BMI status. Among women with an overweight/obese BMI, 25(OH)D <50 nmol/L at 10–14 GW was associated with lower birthweight z-score (0.56; 95% CI: −0.99, −0.13) and length (−1.56 cm; 95% CI: −3.07, −0.06), and at 23–31 GW was associated with shorter length (−2.77 cm; 95% CI: −13.38, −4.98) and lower sum of skinfolds (−9.18 mm; 95% CI: −13.38, −4.98). Among women with a normal BMI, 25(OH)D <50 nmol/L at 10–14 GW was associated with lower sum of skinfolds (−2.64 mm; 95% CI: −5.03, −0.24), at 23–31 GW was associated with larger birthweight z-scores (0.64; 95% CI: 0.03, 1.25), and at 33-39 GW with both higher birthweight z-score (1.22; 95% CI: 0.71, 1.73) and longer length (1.94 cm; 95% CI: 0.37, 3.52). Maternal 25(OH)D status during pregnancy was associated with neonatal anthropometric measures, and the associations were specific to GW of 25(OH)D measurement and prepregnancy BMI.

Foetal ultrasound measurement imputations based on growth curves versus multiple imputation chained equation (MICE)

BACKGROUND

Ultrasound measures are valuable for epidemiologic studies of risk factors for growth restriction. Longitudinal measurements enable investigation of rates of change and identification of windows where growth is impacted more acutely. However, missing data can be problematic in these studies, limiting sample size, ability to characterise windows of vulnerability, and in some instances creating bias. We sought to compare a parametric linear mixed model (LMM) approach to multiple imputation in this setting with multiple imputation by chained equation (MICE) methodology.

METHODS

Ultrasound scans performed for clinical purposes were abstracted from women in the LIFECODES birth cohort (n = 1003) if they were close in time to three study visits (median 18, 26, and 35 weeks' gestation). We created imputed datasets using LMM and MICE and calculated associations between demographic factors and ultrasound parameters cross-sectionally and longitudinally. Results were compared with a complete-case analysis.

RESULTS

Most participants had ultrasounds at 18 weeks' gestation, and ~50% had measurements at 26 and 35 weeks; 100% had birthweight. Associations between demographic factors and ultrasound measures were similar in magnitude, but more precise, when either imputed datasets were used, compared with a complete-case analysis, in both the cross-sectional or longitudinal analyses.

CONCLUSIONS

MICE, though ignoring the non-linear features of the trajectory and within subject correlation, is able to provide reasonable imputation of foetal growth data when compared to LMM. Because it simultaneously imputes missing covariate data and does not require specification of variance structure as in LMM, MICE may be preferable for imputation in this setting.

Large-for-Gestational-Age Neonates in Type 1 Diabetes and Pregnancy: Contribution of Factors Beyond Hyperglycemia

Despite significant reductions in serious adverse perinatal outcomes for women with type 1 diabetes in pregnancy, the opposite effect has been observed for fetal overgrowth and associated complications, such as neonatal hypoglycemia, shoulder dystocia, and admission to the neonatal intensive care unit. In addition, infants born large for gestational age (LGA) have an increased lifetime risk of obesity, diabetes, and chronic disease. Although exposure to hyperglycemia plays an important role, women who seemingly achieve adequate glycemic control in pregnancy continue to experience a greater risk of excess fetal growth, leading to LGA neonates and macrosomia. We review potential contributors to excess fetal growth in pregnancies complicated by type 1 diabetes. In addition to hyperglycemia, we explore the role of glycemic variability, prepregnancy overweight and obesity, gestational weight gain, and maternal lipid levels. Greater understanding of the stimuli that drive excess fetal growth could lead to targeted management strategies in pregnant women with type 1 diabetes, potentially reducing the incidence of LGA neonates and the inherent risk of acute and long-term complications.

Birth weight variants are associated with variable fetal intrauterine growth from 20 weeks of gestation

Fetal intrauterine growth is influenced by complex interactions between the maternal genes, environment and fetal genes. The aim of this study was to assess the effect of GWAS-identified genetic variants associated with birth weight on intrauterine fetal growth in 665 children. Fetal growth was estimated by two-dimensional ultrasound scans at 20, 25 and 32 weeks of gestation and growth trajectories were modeled using mixed linear regression. A genetic risk score (GRS) of birth weight-raising variants was associated with intrauterine growth showing an attenuating effect on the unconditional daily reduction in proportional weight gain of 8.92 × 10-6 percentage points/allele/day (p = 2.0 × 10-4), corresponding to a mean difference of 410 g at 40 weeks of gestation between a child with lowest and highest GRS. Eight variants were independently associated with intrauterine growth throughout the pregnancy, while four variants were associated with fetal growth in the periods 20-25 or 25-32 weeks of gestation, indicating that some variants may act in specific time windows during pregnancy. Four of the intrauterine growth variants were associated with type 2 diabetes, hypertension or BMI in the UK Biobank, which may provide basis for further understanding of the link between intrauterine growth and later risk of metabolic disease.

Can we improve the gestation-adjusted projection (GAP) method for prediction of birth weight in morbidly obese women?. J Matern Fetal Neonatal Med 2018;32:3600-3605. [PMID: 29681190 DOI: 10.1080/14767058.2018.1468882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Objective: The gestation-adjusted projection (GAP) is a method to predict birthweight using population birth data and third trimester ultrasound fetal weight. This method usually utilizes population birth weight data from almost 40 years ago. In 2011, a large cohort of racially diverse infants across the US was included to validate updated birth curves. Our objective was to determine if the updated data would improve the accuracy of the GAP method during the third trimester among obese women. Methods: This secondary analysis of a cohort study included singleton pregnancies of obese women who had fetal growth assessment(s) in the third trimester. The first subgroup (N = 235) included women with a BMI >40 kg/m² who had ultrasounds during 30 + 0-35 + 0 weeks (EARLY) and greater than 35 + 0 weeks (LATE). The second subgroup (N = 431) included women with a BMI 30-35, 40-50, or >50 kg/m² who had an ultrasound during 34 + 0-36 + 6 weeks. Mean absolute percent error was calculated for all GAP methods and compared using paired t-tests. Sensitivity, specificity, and area under the curve for diagnosis of birth weight >4000 grams were also estimated for each GAP method. Results: The mean absolute percent error for the first subgroup (N = 235) using historical population birth weights was 7.4-7.9%. After using updated population birth weight curves using all neonates, the mean absolute percent error for the first subgroup ranged between 7.6 and 9.4%. GAP predictions using all neonates, as well as male and female-specific birth data compared to the historical population data during both the EARLY and LATE periods were significantly worse (p < .01). The mean absolute percent error for the second subgroup (N = 431) using historical population birth weights ranged from 7.2 to 7.9%. The absolute percent error using gender-specific compared to historical data was significant in the BMI 30-35 group (male 8.1% versus historical 7.6%, p < .01, female 8.1% versus historical 7.6%, p < .01). The differences in absolute percent error between historical and updated population data became less evident in the BMI 40-50 and >50-kg/m² groups (p = .05 and p = .15, respectively) though still overall performed worse with the updated data. Conclusions: Prediction of birth weight using the GAP method does not seem to be improved among obese women after using updated population data. Alternatively, modeling techniques may need to be applied to improve the accuracy of the GAP method.

The INTERGROWTH-21st fetal growth standards: toward the global integration of pregnancy and pediatric care

The purpose of the INTERGROWTH-21^st project was to develop international, prescriptive standards for fetal growth assessed by ultrasound and fundal height, preterm postnatal growth, newborn size and body composition, maternal weight gain, and infant development at the age of 2 years. Hence, we have produced, based on World Health Organization recommendations, the first comprehensive set of international standards of optimal fetal and newborn growth that perfectly match the existing World Health Organization child growth standards. Uniquely, the same population was followed up longitudinally from 9 weeks of fetal life to 2 years of age, with growth, health, and nutritional status assessment at 2 years supporting the appropriateness of the population for construction of growth standards. The resulting package of clinical tools allows, for the first time, growth and development to be monitored from early pregnancy to infancy. The INTERGROWTH-21^st fetal growth standards, which are based on observing >4500 healthy pregnancies, nested in a study of >59,000 pregnancies from populations with low rates of adverse perinatal outcomes, show how fetuses should grow-rather than the more limited objective of past references, which describe how they have grown at specific times and locations. Our work has confirmed the fundamental biological principle that variation in human growth across different populations is mostly dependent on environmental, nutritional, and socioeconomic factors. We found that when mothers' nutritional and health needs are met and there are few environmental constraints on growth, <3.5% of the total variability of skeletal growth was due to differences between populations. We propose that not recognizing the concept of optimal growth could deprive the most vulnerable mothers and their babies of optimal care, because local growth charts normalize those at highest risk for growth restriction and overweight, and can be valuable for policymakers to ensure rigorous evaluation and effective resource allocation. We strongly encourage colleagues to join efforts to provide integrated, evidence-based growth monitoring to pregnant women and their infants worldwide. Presently, there are 23.3 million infants born small for gestational age in low- to middle-income countries according to the INTERGROWTH-21^st newborn size standards. We suggest that misclassification of these infants by using local charts could affect the delivery of optimal health care.