Steroid Hormones in Cord Blood Mediate the Association Between Maternal Prepregnancy BMI and Birth Weight

Associations of ambient temperature and total cloud cover during pregnancy with newborn vitamin D status

OBJECTIVES

We aimed to estimate the effects of temperature and total cloud cover before birth on newborn vitamin D status.

STUDY DESIGN

Prospective birth cohort.

METHODS

This study included 2055 mother-newborn pairs in Wuhan, Hubei province, China. The data of temperature and total cloud cover from 30 days before birth were collected, and cord blood 25-hydroxyvitamin D [25(OH)D] were determined. Restricted cubic spline regression models, multiple linear regression models, and logistic regression models were applied to estimate the associations.

RESULTS

A "J" shaped curve was observed between temperature and vitamin D status, and an inverse "J" shaped curve was observed between total cloud cover and vitamin D status. Compared to the fourth quartile (75-100th percentile, Q4) of average temperature (30 days before birth), the odds ratio (OR) for Q1 (0-25th percentile) associated with the vitamin D deficiency occurrence (<20 ng/mL) was 3.63 (95% CI, 1.54, 8.65). Compared to Q1 of the average total cloud cover (30 days before birth), the OR associated with the occurrence of vitamin D deficiency was 2.38 (95% CI, 1.63, 3.50) for the Q4.

CONCLUSIONS

Low temperature and high cloud cover before delivery were significantly associated with an increased probability of vitamin D deficiency in newborns. The findings suggested that pregnancy women lacking sufficient sunlight exposure still need vitamin D supplement to overcome the potential vitamin D deficiency status.

Associations between maternal urinary rare earth elements during pregnancy and birth weight-for-gestational age: Roles of cord blood vitamin D levels

Prenatal exposure to rare earth elements (REEs) may contribute to adverse birth outcomes in previous studies. Cord blood vitamin D has been suggested to modify or mediate the effects of environmental exposures. However, none has investigated these roles of cord blood vitamin D in the associations of prenatal exposure to REEs with fetal growth. Maternal trimester-specific urinary concentrations of 13 REEs, cord blood total 25-hydroxyvitamin D at delivery, and birth weight (BW)-for-gestational age (GA) were determined in 710 mother-newborn pairs from Wuhan, China. Higher maternal average urinary concentrations of europium (Eu), gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er), and ytterbium (Yb) across three trimesters, either individually or jointly, were significantly associated with lower BW-for-GA Z-scores and higher odds of small for gestational age (SGA) [β = -0.092; 95 % confidence interval (CI): -0.149, -0.035 for BW-for-GA Z-scores, and odds ratio = 1.60; 95 % CI: 1.14, 2.24 for SGA involved in each unit increase in weighted quantile sum index of REEs mixture]. When stratified by cord blood vitamin D levels, the associations mentioned above persisted in participants with relatively low vitamin D levels (<13.94 μg/L, the first tertile of distribution), but not among those with relatively high levels (≥13.94 μg/L) (all p-values for interaction < 0.05). The mediation analyses taking account of exposure-mediator interaction showed that the relationships between REEs (as individual and mixture) exposure and lower BW-for-GA were partly mediated through decreasing cord blood vitamin D levels. The proportions mediated by cord blood vitamin D levels were 24.48 % for BW-for-GA Z-scores and 29.05 % for SGA corresponding to the REEs mixture exposure. Conclusively, our study revealed that prenatal exposures to Eu, Gd, Dy, Ho, Er, and Yb were related to fetal growth restriction. Cord blood vitamin D might alleviate toxic effects of these REEs and its reduction might partly mediate REE-induced fetal growth restriction.

Mediation effect of cord blood cortisol levels between maternal prepregnancy body mass index and birth weight: a hospital-based cross-sectional study

BACKGROUND

Changes in maternal weight affect the maternal and fetal hypothalamic-pituitary-adrenal axis, influencing birth weight and contributing to the fetal origin of adult diseases (Barker's hypothesis). This study primarily focused on cord blood cortisol levels and identified the association between maternal prepregnancy body mass index (pre-BMI) and birth weight. It also assessed cord blood lipid profile changes related to maternal pre-BMI, birth weight, and cord blood cortisol levels.

PURPOSE

To study the mediation effect of cord blood cortisol level between maternal pre-BMI and birth weight and its correlation with cord blood lipid profile.

METHODS

A total of 169 maternal-neonatal pairs were included at 2 tertiary care centers. Mediation analysis was used to estimate the extent of the association between maternal weight changes and birth weight.

RESULTS

For each unit increase in maternal pre-BMI, birth weight increased by 90.5 g; for every kilogram increase in gestational weight, birth weight increased by 128.44 g. No considerable mediation effect of cortisol was found between pre-BMI and gestational weight gain or between rate of weight gain and birth weight. Pre-BMI and birth weight had a significant negative correlation with high-density lipoprotein cholesterol (HDL-C) levels, i.e., HDL-C was decreased by 1.1 mg/dL for every unit increase in BMI (P=0.017) and for every 100-g increase in birth weight, HDL-C decreased by 0.6 mg/dL (P=0.046). A significant positive correlation was found between cord blood lipid profile and cortisol levels, especially HDL-C (P=0.041).

CONCLUSION

Cord blood cortisol levels did not mediate the association between maternal weight change and birth weight. A positive correlation was noted between cord blood cortisol levels and HDL-C level. Cord blood HDL-C level was negatively correlated with maternal pre-BMI and birth weight.

Associations between six common per- and polyfluoroalkyl substances and estrogens in neonates of China

Experimental studies suggested per- and polyfluoroalkyl substances (PFASs) may disrupt estrogens in animals, however, the epidemiological evidence on the associations of PFASs with estrogens is sparse. We investigated the associations of legacy PFASs and their alternatives, including F-53B, the perfluorooctane sulfonate (PFOS) replacement that is specifically and commonly used in China, with estrogen concentrations in newborns. We quantified six PFASs and three estrogens in the cord sera of 942 newborns from a birth cohort in Wuhan, China, between 2013 and 2014. After adjusting for confounders and correcting for multiple comparisons, we observed that both legacy PFASs and their alternatives were associated with higher serum levels of estradiol (E2). Some of the PFASs were associated with increasing levels of estrone (E1) and estriol (E3). Analysis of PFASs in mixture using weighted quantile sum regressions showed that F-53B contributed 20.1% and 48.5% to the associations between PFASs and E1 and E2, respectively. This study provided epidemiological data on the associations between common PFAS exposures and estrogens in newborns. Additional toxicology studies are needed to fully understand the effects of PFASs on estrogens and the mechanisms.