In a double-blind zinc trial in low-income, pregnant adolescents thought to be at risk for poor zinc nutriture, subjects were randomly assigned to receive 30 mg zinc (gluconate) or placebo. Response to zinc was related to maternal weight. Infants of normal-weight mothers given zinc had reduced rates of prematurity (p = 0.05) and assisted respiration (p = 0.006). Underweight multiparas given zinc had longer gestational lengths (p = 0.008) than did subjects given the placebo. Multiple stepwise regression analysis, used to identify predictors of infant size, revealed that 14-26% more variance was accounted for in the zinc than in the placebo group. Except for gestational age, the predictors selected were entirely different in the two groups. The zinc group had a positive toxemia screen more often, which did not appear to affect outcome. Zinc supplementation improved pregnancy outcome in normal-weight women and in underweight multiparas. The nonresponse in underweight primiparas was perhaps due to multiple limiting factors.

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A study was conducted at Charity Hospital, New Orleans, among 272 adolescent pregnant women to ascertain the relationship of pregnancy outcome to plasma zinc level measured once at the time of enrollment. Regression analyses were performed on zinc status versus parameters concerning success of pregnancy corrected for gestational stage at specimen collection. Analysis of variance was performed on groups according to presence or absence of complications, with analyses of covariance used to analyze dichotomous groups. Low, though widely variable, plasma zinc levels were found (mean = 58 +/- 12.6 micrograms/dl). Zinc values differed significantly by gestational stage at collection, the regression coefficient indicating a decline of 0.07 micrograms/dl/day. Plasma zinc level correlated significantly with Hb, red blood cells, ferritin, and folic acid. As to course of pregnancy, women experiencing hypertension/toxemia were found to have significantly lower plasma zinc level. Among infants displaying congenital defects at birth those with undescended testes and metatarsus varus were delivered by mothers whose plasma zinc was well below the mean for the group. These findings indicate the need to investigate the influence of dietary patterns and zinc intake on maternal plasma zinc level and pregnancy outcome, further delineating the role of zinc in human reproduction, particularly hypertension of pregnancy.