Fetal adrenal function in normal and insulin-dependent diabetic pregnancies

Abstract

Objective: The functional role of fetal adrenal gland in processes of prenatal and postnatal adaptation is known. Fetal endocrine responses in normal pregnancy and pregnancy, complicated by maternal insulin-dependent diabetes mellitus (IDD) were examined in this study.

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Methods: Fetal blood (FB) and amniotic fluid (AF) samples were obtained by transabdominal cordocentesis and amniocentesis in 24 women with IDD, at 34-37 weeks gestation and 11 women with normal pregnancies at 30-37 weeks gestation. Normal fetal cortisol synthesis dynamic was examined in 17 normal pregnancies at 20-30 weeks gestation. Maternal venous blood was collected immediately after cordocentesis. Cortisol plasma and AF concentrations were measured using immunoenzimatic assay kit. The statistics was made using Student t-test and correlation analysis.

Results: No significant difference in mean fetal cortisol concentrations between different gestation ages of normal pregnancy was found: 49,9±22 nmol/l at 20-25 weeks, 34,5±52,5 nmol/l at 25-30 weeks and 52,5±12 nmol/l at 25-30 weeks gestation. But cortisol levels in FB increased gradually in the HI trimester of normal pregnancy from 22,4 nmol/l at 26 weeks to 69,4 nmol/l at 37 weeks gestation and was significantly associated with gestational age (r=0,766, p<0,01). Statistically significant fetal hypercortisolemia was observed in pregnancies, complicated by IDD: cortisol levels in FB were 95,9±41,1 nmol/l in compare with the same normal figures 52,5±12 nmol/l. Mean cortisol levels in AF in diabetic pregnancies were also higher (M=95,7±36,2 nmol/l) from normal (M=71,3±36,2 nmol/l). There was no difference in maternal cortisol concentrations in normal pregnancies (M=688,2±107,8 nmol/l) and diabetic pregnancies (M=788,9±196,07 nmol/l). Significant correlation between fetal and maternal cortisol concentrations was found both in normal (r=0,450, p<0,05) and diabetic pregnancies (r=0,433, p<0,05).

Conclusions: Dynamic of fetal cortisol levels in normal pregnancy showed increased activity of the fetal adrenal in late gestation age. This process considered to be one of the factors initiated parturition. Association between fetal and maternal cortisol concentrations acknowledged the active placenta role in fetal cortisol metabolism and transplacental transport of maternal cortisol to fetus. Fetal hypercortisolemia may be the fetal adrenal adaptation reaction to chronic stress associated fetal hyperinsulinemia in diabetic pregnancies.