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

We used stature and measurement of knee height to measure continued maternal growth during adolescent pregnancy in a sample of young gravidas (primigravidas and multiparas) and mature pregnant control subjects. Growth during pregnancy has been masked by a tendency of all gravidas to shrink while pregnant (approximately 0.5 cm over 6 mo of observation). Consequently, growth of many adolescent gravidas has not been clinically apparent. There was no effect on maternal growth during a first pregnancy in adolescence but this may be a result of the relatively good prepregnant nutrition status of the young gravidas in developed countries. Maternal growth during pregnancy, however, is associated with significantly decreased (-282 g, p less than 0.05) birth weight for infants when maternal growth continues during a subsequent adolescent pregnancy. This observation is consistent with the hypothesized competition between the metabolic demands of the growing adolescent mother and the nutrient needs of her developing fetus.

Low gynaecological age, defined as conception within 2 completed years of menarche, was examined for its association with preterm birth, using data from a geographically based cohort of over 1700 young primigravidae aged 18 or younger at start of prenatal care. After stratifying by chronological age and controlling for confounding variables, low gynaecological age was associated with almost double the risk of preterm delivery whether estimated from the mother's last menstrual period (adjusted odds ratio (AOR) = 1.77, 95% CI 1.19-2.64) or using the obstetric estimate of gestation (AOR = 2.10, 95% CI 1.36-3.25). Low gynaecological age was also associated with an increase in risk of low birthweight (LBW) (AOR = 1.70, 95% CI 1.01-2.88), but not of small-for-gestational-age babies (AOR = 0.94, 95% CI 0.49-1.81). Thus low gynaecological age may be an important addition to assessment systems to detect women at risk of preterm labour and delivery.

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A B S T R A C T Aldosterone concentrations in plasma of women on normal sodium intake undergoing cesarean section were 3.7 ±1.4 ng/100 ml (mean ±1 SD). These values were significantly lower (P <0.001) than those observed in mothers on normal sodium diet, delivered by the vaginal route (14.9 +7.0 ng/100 ml). A significant elevation (P < 0.001) of the concentrations was found if the mothers had been on sodium restriction and/or diuretics (44.9 ±24.2 ng/100 ml). In supine position, adult nonpregnant subjects have aldosterone concentrations in plasma of 1.7 ±1.4 ng/100 ml on normal sodium intake and of 16.7 ±8.1 ng/100 ml on low sodium diet.Simultaneous determinations of aldosterone levels in cord blood showed that cord values were significantly higher than those of the corresponding mother (P < 0.01 by paired t test). However, values in cord blood of infants born to mothers on a normal sodium intake were significantly lower (P < 0.005) than those of infants whose mothers had required low sodium diet and/or diuretics during their pregnancy.Aldosterone concentrations in plasma of infants 1-72 hr of age and born to mothers on normal sodium intake were 25.9 ±11.7 ng/100 ml (mean ±1 SD). These values were significantly lower (P < 0.005) than those of infants born to mothers on restricted sodium intake with or without diuretics (80.3 ±54.4 ng/100 ml). The concentrations at birth were not significantly different from those observed during the first 3 days of life (P>0.6).

A B S T R A C T The transplacental passage and the production of aldosterone were studied in late pregnancy during a constant infusion of 1,2-aldosterone-3H to mothers at the time of elective cesarean section.It was found that, while maternal aldosterone crossed the placenta, there was a significant secretion of aldosterone by the fetus. The aldosterone concentration in fetal plasma was 2-12 times higher than that of the corresponding mothers.Pregnancy had no effect on the metabolic clearance rate of aldosterone, but it increased the rate of production of this steroid. However, the increments that we observed were smaller than those reported in previous reports. The discrepancy was probably due to differences in body posture, our subjects being supine for at least 10 hr at the time of study.