Associations of maternal early-pregnancy blood glucose and insulin concentrations with DNA methylation in newborns

BACKGROUND

Intrauterine exposure to a disturbed maternal glucose metabolism is associated with adverse offspring outcomes. DNA methylation is a potential mechanism underlying these associations. We examined whether maternal early-pregnancy glucose and insulin concentrations are associated with newborn DNA methylation. In a population-based prospective cohort study among 935 pregnant women, maternal plasma concentrations of non-fasting glucose and insulin were measured at a median of 13.1 weeks of gestation (95% range 9.4-17.4). DNA methylation was measured using the Infinium HumanMethylation450 BeadChip (Ilumina). We analyzed associations of maternal early-pregnancy glucose and insulin concentrations with single-CpG DNA methylation using robust linear regression models. Differentially methylated regions were analyzed using the dmrff package in R. We stratified the analyses on normal weight versus overweight or obese women. We also performed a look-up of CpGs and differently methylated regions from previous studies to be associated with maternal gestational diabetes, hyperglycemia or hyperinsulinemia, or with type 2 diabetes in adults.

RESULTS

Maternal early-pregnancy glucose and insulin concentrations were not associated with DNA methylation at single CpGs nor with differentially methylated regions in the total group. In analyses stratified on maternal BMI, maternal early-pregnancy glucose concentrations were associated with DNA methylation at one CpG (cg03617420, XKR6) among normal weight women and at another (cg12081946, IL17D) among overweight or obese women. No stratum-specific associations were found for maternal early-pregnancy insulin concentrations. The two CpGs were not associated with birth weight or childhood glycemic measures (p values > 0.1). Maternal early-pregnancy insulin concentrations were associated with one CpG known to be related to adult type 2 diabetes. Enrichment among nominally significant findings in our maternal early-pregnancy glucose concentrations was found for CpGs identified in a previous study on adult type 2 diabetes.

CONCLUSIONS

Maternal early-pregnancy glucose concentrations, but not insulin concentrations, were associated with DNA methylation at one CpG each in the subgroups of normal weight and of overweight or obese women. No associations were present in the full group. The role of these CpGs in mechanisms underlying offspring health outcomes needs further study. Future studies should replicate our results in larger samples with early-pregnancy information on maternal fasting glucose metabolism.

High maternal early-pregnancy blood glucose levels are associated with altered fetal growth and increased risk of adverse birth outcomes

AIMS/HYPOTHESIS

The study aimed to assess the associations of maternal early-pregnancy blood glucose levels with fetal growth throughout pregnancy and the risks of adverse birth outcomes.

METHODS

In a population-based prospective cohort study among 6116 pregnant women, maternal non-fasting glucose levels were measured in blood plasma at a median 13.2 weeks of gestation (95% range 9.6-17.6). We measured fetal growth by ultrasound in each pregnancy period. We obtained information about birth outcomes from medical records and maternal sociodemographic and lifestyle factors from questionnaires.

RESULTS

Higher maternal early-pregnancy non-fasting glucose levels were associated with altered fetal growth patterns, characterised by decreased fetal growth rates in mid-pregnancy and increased fetal growth rates from late pregnancy onwards, resulting in an increased length and weight at birth (p ≤0.05 for all). A weaker association of maternal early-pregnancy non-fasting glucose levels with fetal head circumference growth rates was present. Higher maternal early-pregnancy non-fasting glucose levels were also associated with an increased risk of delivering a large-for-gestational-age infant, but decreased risk of delivering a small-for-gestational-age infant (OR 1.28 [95% CI 1.16, 1.41], OR 0.88 [95% CI 0.79, 0.98] per mmol/l increase in maternal early-pregnancy non-fasting glucose levels, respectively). These associations were not explained by maternal sociodemographic factors, lifestyle factors or BMI. Maternal early-pregnancy non-fasting glucose levels were not associated with preterm birth or delivery complications.

CONCLUSIONS/INTERPRETATION

Higher maternal early-pregnancy non-fasting glucose levels are associated with decreased fetal growth rates in mid-pregnancy and increased fetal growth rates from late pregnancy onwards, and an increased risk of delivering a large-for-gestational-age infant. Future preventive strategies need to focus on screening for an impaired maternal glucose metabolism from preconception and early pregnancy onwards to improve birth outcomes.

Pregnancy phthalate metabolite concentrations and infant birth weight by gradations of maternal glucose tolerance

BACKGROUND

Higher birth weight is an important adverse outcome associated with hyperglycemia in pregnancy. Recent studies suggest that phthalate exposure is associated with elevated glucose levels in pregnant women, with implications for higher birth weight in the offspring. No study to date has investigated the association between prenatal phthalate exposure on infant high birth weight accounting for the range of pregnancy glucose levels.

METHODS

A total of 350 women participating in an ongoing pregnancy cohort had data available on urinary phthalate metabolite concentrations at up to four time points across pregnancy. Urinary phthalate metabolites were averaged across pregnancy and log-transformed, specific gravity-adjusted and analyzed in quartiles. Birth weight was examined continuously (in grams), as well as dichotomized as large for gestational age (>90^th percentile). Glucose levels were assessed based on Results from 50-g glucose challenge tests as a part of screening for gestational diabetes conducted at 24-28 weeks gestation, and grouped into 3 categories <120 mg/dL, 120-<140 mg/dL and ≥140 mg/dL. Multivariable linear regression was performed, adjusting for potential confounders in the overall population and stratified by pregnancy glucose levels.

RESULTS

Approximately 20% of infants born to women with glucose levels ≥140 mg/dL were large for gestational age. Average mono-ethyl phthalate (MEP) concentrations were higher among women who had glucose levels ≥140 mg/dL (geometric mean 140.9 μg/L; 95% CI: 91.6-216.8); however, higher MEP concentrations were not associated with higher birth weight. When stratified by maternal glucose levels, there was a suggestive association between higher concentrations of mono-(3-carboxypropyl) phthalate (MCPP) and higher birth weight among women with glucose levels ≥140 mg/dL (adj. birth weight: 569.2 g; 95% CI: 14.1, 1178.2).

CONCLUSIONS

Higher urinary phthalate metabolite concentrations were not significantly associated with higher birth weight. Counter to our hypothesis, women with higher glucose levels and higher urinary phthalate metabolites did not deliver babies with higher birth weight.

Maternal overweight is not an independent risk factor for increased birth weight, leptin and insulin in newborns of gestational diabetic women: observations from the prospective 'EaCH' cohort study

BACKGROUND

Both gestational diabetes mellitus (GDM) as well as overweight/obesity during pregnancy are risk factors for detrimental anthropometric and hormonal neonatal outcomes, identified to 'program' adverse health predispositions later on. While overweight/obesity are major determinants of GDM, independent effects on critical birth outcomes remain unclear. Thus, the aim of the present study was to evaluate, in women with GDM, the relative/independent impact of overweight/obesity vs. altered glucose metabolism on newborn parameters.

METHODS

The prospective observational 'Early CHARITÉ (EaCH)' cohort study primarily focuses on early developmental origins of unfavorable health outcomes through pre- and/or early postnatal exposure to a 'diabetogenic/adipogenic' environment. It includes 205 mother-child dyads, recruited between 2007 and 2010, from women with treated GDM and delivery at the Clinic of Obstetrics, Charité - Universitätsmedizin Berlin, Germany. Recruitment, therapy, metabolite/hormone analyses, and data evaluation were performed according to standardized guidelines and protocols. This report specifically aimed to identify maternal anthropometric and metabolic determinants of anthropometric and critical hormonal birth outcomes in 'EaCH'.

RESULTS

Group comparisons, Spearman's correlations and unadjusted linear regression analyses initially confirmed that increased maternal prepregnancy body-mass-index (BMI) is a significant factor for elevated birth weight, cord-blood insulin and leptin (all P < 0.05). However, consideration of and adjustment for maternal glucose during late pregnancy showed that no maternal anthropometric parameter (weight, BMI, gestational weight gain) remained significant (all n.s.). In contrast, even after adjustment for maternal anthropometrics, third trimester glucose values (fasting and postprandial glucose at 32nd and 36th weeks' gestation, HbA1c in 3rd trimester and at delivery), were clearly positively associated with critical birth outcomes (all P < 0.05).

CONCLUSIONS

Neither overweight/obesity nor gestational weight gain appear to be independent determinants of increased birth weight, insulin and leptin. Rather, 3rd trimester glycemia seems to be crucial for respective neonatal outcomes. Thus, gestational care and future research studies should greatly consider late pregnancy glucose in overweight/obese women with or without GDM, for evaluation of critical causes and interventional strategies against 'perinatal programming of diabesity' in the offspring.

Associations of Maternal Leptin with Neonatal Adiposity Differ according to Pregravid Weight

BACKGROUND

During pregnancy, maternal circulating leptin is released by maternal adipose tissue and the placenta, and may have a role in fetal development.

OBJECTIVES

We investigated maternal leptinemia and glycemia associations with neonatal adiposity, taking into account pregravid weight status.

METHODS

We included 235 pregnant women from the Genetics of Glucose Regulation in Gestation and Growth prospective cohort with data: blood samples collected during the 2nd trimester, an oral glucose tolerance test (OGTT), and the measured leptin and glucose levels. As an integrated measure of maternal leptin exposure, we calculated the area under the curve for maternal leptin at the OGTT (AUCleptin). Within 72 h of delivery, we measured the triceps, biceps, subscapular, and suprailiac skinfold thicknesses (SFTs); the sum of these SFTs represented neonatal adiposity. We conducted a regression analysis to assess the maternal metabolic determinants of neonatal adiposity, adjusting for parity, smoking status, maternal triglyceride levels, gestational weight gain, placental weight, delivery mode, neonate sex, and gestational age at delivery.

RESULTS

The pregravid BMI of the participating women was 23.3 (21.2-27.0). In the 2nd trimester, maternal AUCleptin was 1,292.0 (767.0-2,222.5) (ng × min)/mL, and fasting glucose levels were 4.2 ± 0.4 mmol/L. At delivery, the neonatal sum of 4 SFTs was 17.9 ± 3.3 mm. Higher maternal leptinemia was associated with higher neonatal adiposity (β = 4.23 mm [SE = 1.77] per log-AUCleptin; p = 0.02) in mothers with a BMI ≥25, independently of confounders and maternal glycemia, but not in mothers with a BMI <25. Higher maternal fasting glucose was associated with higher neonatal adiposity (β = 0.88 mm [SE = 0.30] per SD glucose; p = 0.005) in mothers with a BMI <25, independently of confounders and maternal leptinemia.

CONCLUSION

Maternal leptinemia may be associated with neonatal adiposity in offspring from overweight/obese mothers, independently of maternal glycemia.