Comparison of fetal plasma cortisol level between eutrophic and hypotrophic newborns.

We tested two groups of singletons born at term: fifty-six eutrophic newborns and 56 hypotrophic subjects. They were selected randomly from all newborns delivered by vaginal route between 8 and 14 hours. Excluded were preeclampsia, diabetes, labours longer than 12 hours and newborns with malformations. Written informed consent was obtained from all women and data were collected before and after labour. Umbilical cord blood samples were obtained immediately following the delivery and plasma cortisol concentrations were measured by radioimmunoassay. The groups did not differ significantly regarding maternal age, parity, gestational age and Apgar score, but birth weight was significant differed (p < 0.001). In addition, eutrophic newborns had significantly elevated cortisol levels (457.7 nmol/L, 321.8-696.6 nmol/L) compared with hypotrophic newborns (320.5 nmol/L, 215.1-578.7 nmol/L, p < 0.001). The role of fetal cortisol in intrauterine growth restriction (IUGR) pregnancy and labour is uncertain, but fetal plasma cortisol levels may be lower in IUGR newborns.