Weight gained at an excessive rate by women with a pregravid BMI in the normal range does not greatly enhance fetal growth and gestation duration, contributing instead to postpartum maternal overweight.

A constant infusion of 14 C-cortisol and 3 H-cortisone for 4 hr was given to six pregnant women, at term, at the time of elective cesarean section. Radioactive and nonradioactive cortisol (F) and cortisone (E) concentrations were determined in maternal and cord plasma at the time when the concentration of the radioactive steroids had reached a plateau. Metabolic clearance rates (MCR), plasma levels of endogenous F and E, blood production rates (BP), conversion ratios (Cr), and transfer constants ([p] BB values) were calculated and compared with those obtained in eight nonpregnant women, half of whom took contraceptive medication (subjects taking "the pill") and half of whom did not (control subjects).The MCR (F) of women near term, control subjects, and women receiving contraceptive treatment were (mean db SD) 133 ± 47, 141 ± 37, and 62 db 24 liters/24 hr, respectively. The latter was significantly lower than the other two. The MCR (E) were similar in all three groups of subjects and 4-7 times greater than MCR (F).The ratio of the endogenous F/E for control subjects was significantly lower (4.8 ± 0.6) than that for women on the pill (9.0 ± 1.6) or for pregnant women (7.5 ± 1.7). In contrast to their mothers, the neonates had an F/E ratio of 0.85 ± 0.34 with a mother /cord ratio for F of 4.9 ± 2.5 and for E of 0.50 ± 0.15.In eight fetuses of 3-6 months of gestational age, plasma concentrations of F (2.1 ± 1.2 jug/100 ml) and E (4.7 ± 3.3 jug/100 ml) were lower than those of six neonates (6.3 db 2.9 for F and 7.2 ± 1.2 /ig/100 ml for E).For control subjects, the Cr F^E was significantly higher and the Cr E^F significantly lower than these ratios for pregnant women and for women on contraceptive medication. From the values of BP (F) for each subject and the corresponding transfer constant [P]BB E it was estimated that all the BP (E) for the subjects studied arose from BP (F), which suggested that, within the limits of error of the methods used, there was no E secretion. SpeculationFrom previous studies in sheep, it was demonstrated that cortisol crossed the placenta from the mother to the fetus but that the fetus near term was also able to secrete cor-509 510 BEITINS ET AL.tisol. In this study of pregnant women we were able to calculate the maternal contribution to the fetal cortisol and cortisone concentration and to show that the fetus secretes three-fourths of its cortisol but that its cortisone was mainly maternal in origin. We were also able to show that cortisol and cortisone concentrations, similar to those at term, existed in utero as early as the 3rd month. We therefore speculate that the human fetal adrenal is capable of corticosteroid secretion early in pregnancy.

No abstract