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

Abstract

Objective: Maternal overweight has been associated with increasing offspring birth weight, but epidemiological data on potential biological mechanisms are limited. This study aimed to examine whether steroid hormones mediate the association between maternal prepregnancy BMI (pre-BMI) and birth weight. Methods: This study involving 2,039 participants was conducted from an ongoing cohort study in Wuhan, China. Mediation analysis was used to identify the extent to which steroid hormones mediated associations. Results: Each one-unit increase in pre-BMI was significantly associated with lower log 2 -transformed cord blood levels of cortisol and corticosterone. Levels of cortisol and corticosterone were also negatively associated with birth weight. It was estimated that corticosterone mediated 3.48% of the association between pre-BMI and birth weight, and no significant mediation effect was observed in cortisol. After stratification by maternal gestational weight gain (GWG; within or in excess of the Institute of Medicine [IOM] guidelines), the associations of pre-BMI with cortisol and corticosterone levels were significant in the women with GWG > IOM but not in women with GWG ≤ IOM. When the mediation analysis in the women with GWG > IOM was limited, the mediation effects of cord blood cortisol and corticosterone were both significant (P < 0.05). Conclusions: Cord blood cortisol and corticosterone partially mediate the association of increased maternal pre-BMI with higher birth weight.

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

“…A study by Shuna et al analyzed all the steroid hormones in the maternalplacental-fetal unit in their large birth cohort, which showed a partial mediation effect of 3.48% with corticosterone and in mothers with GWG>IOM, 4.33% and 5.38% mediation with cortisol and corticosterone respectively. 12) In our study, cord blood HDL-C levels had a negative correlation with both maternal pre-BMI and with birth weight. Studies by Mandraha S et al and Pac-Kozuchowska E et al…”

“…However, we cannot rule out the influence of other steroid hormones in the maternal-placental-fetal unit on the birth weight of the newborn. A study by Jin et al [ 12 ] analyzed all the steroid hormones in the maternal-placental-fetal unit in their large birth cohort, which showed a partial mediation effect of 3.48% with corticosterone and in mothers with GWG>IOM, 4.33% and 5.38% mediation with cortisol and corticosterone respectively.…”

“…8,9,10) Cortisol, the most abundant glucocorticoid during pregnancy, accounts for 95% of glucocorticoid activity. 11,12) It is crucial for fetal growth and organ maturation. Cortisol is the result of the HPA axis [corticotropin releasing hormone released from the hypothalamus…”

“…Cortisol, the most abundant glucocorticoid during pregnancy, accounts for 95% of glucocorticoid activity [ 11 , 12 ]. It is crucial for fetal growth and organ maturation.…”

Does cord blood cortisol have a mediating effect on maternal prepregnancy body mass index and birth weight?

“…than the Institute of Medicine's recommendation. 8) Therefore, if the basic mechanisms connecting pre-BMI or GWG and birth weight are identified, achieving an optimal pre-BMI and GWG may reduce obstetric complications as well as the proportion of LGA, macrosomia, SGA, or LBW.…”