Women In Term Labor Research Articles

Alterations in vitamin D and calcium metabolism with magnesium sulfate treatment of preeclampsia

Our purpose was to determine the effects of magnesium sulfate therapy on preeclamptic women and their fetuses with regard to the hormones and ions involved with calcium homeostasis, including 1,25-dihydroxyvitamin D, 25-hydroxyvitamin D, parathyroid hormone, and calcium. The study group comprised 15 preeclamptic women at term treated with magnesium sulfate during labor. Controls were seven normal women in term labor. The hormones and ions were measured in maternal blood obtained at the onset of labor and at delivery and in umbilical venous (fetal) blood. Baseline maternal levels of 25-hydroxyvitamin D and parathyroid hormone were lower in preeclamptics than in controls. Magnesium infusion led to significant elevations in magnesium, 1,25-dihydroxyvitamin D, 25-hydroxyvitamin D, and parathyroid hormone levels and lowered calcium concentrations. Fetuses of treated subjects demonstrated reductions in serum total and ionized calcium and elevations of 1,25-dihydroxyvitamin D and parathyroid hormone. Magnesium sulfate infusion causes reductions in both maternal and fetal calcium levels. Both mother and fetus respond with increased 1,25-dihydroxyvitamin D and parathyroid hormone levels, which may prevent more severe maternal, fetal, and neonatal hypocalcemia.

Facts and Artifacts About Anemia and Preterm Delivery

The effect of anemia (hematocrit less than or equal to 0.34) on subsequent preterm birth was prospectively studied in 35,423 pregnancies. The incidence of preterm birth among women with and without anemia at each week during the third trimester was compared. Early in the third trimester, there was a weak association between anemia and preterm delivery. However, anemia early in the third trimester did not account for the substantial increase in preterm birth seen among black women. Anemia after 30 weeks' gestation was not associated with preterm birth. Among women delivering term infants weighing 2500 g or more, the mean hematocrit rose 0.029 among black women and 0.021 among white women from 25 weeks to term. Compared with hematocrits at 40 weeks' gestation, the odds ratios for anemia reached a maximum at 28 weeks and fell sharply as term approached. When the hematocrits of women in term labor were compared with those of women in preterm labor, a spurious dose-response effect for anemia was created. We conclude that anemia is not a strong factor in the pathogenesis of preterm birth and that comparison of hematocrits from women who are in preterm and term labor produces biased results.