Whether taking multivitamins or folate around the time of conception can reduce a woman's risk of having a child with a neural-tube defect is controversial. To investigate this question, we examined the periconceptional use of vitamin supplements by women who had a conceptus with a neural-tube defect (n = 571), women who had had a stillbirth or a conceptus with another malformation (n = 546), and women who had had a normal conceptus (n = 573). Women with conceptuses with neural-tube defects were identified either prenatally or postnatally and were matched to control mothers for gestational age. To minimize recall bias, we interviewed nearly all the women within five months of the diagnosis of a birth defect or the birth of the infant (mean, 84 days); information on vitamin use was obtained by an interviewer who was unaware of the outcome of pregnancy. The rate of periconceptional multivitamin use among the mothers of infants with neural-tube defects (15.8 percent) was not significantly different from the rate among mothers in either the abnormal or the normal control group (14.1 percent and 15.9 percent, respectively). After adjustment for potential confounding factors, the odds ratio for having an infant with a neural-tube defect among women classified as having had full supplementation with multivitamins was 0.95 as compared with the mothers of the abnormal infants (95 percent confidence interval, 0.78 to 1.14) and 1.00 as compared with the mothers of normal infants (95 percent confidence interval, 0.83 to 1.20). There were no differences among the groups in the use of folate supplements. The adjusted odds ratio for having an infant with a neural-tube defect among those receiving the recommended daily allowance of folate was 0.97 as compared with the mothers of abnormal infants (95 percent confidence interval, 0.79 to 1.18) and 0.98 as compared with the mothers of normal infants (95 percent confidence interval, 0.80 to 1.20). We conclude that the periconceptional use of multivitamins or folate-containing supplements by American women does not decrease the risk of having an infant with a neural-tube defect.

Insulin-dependent diabetic women have been shown to have subnormal hormone levels in the first trimester of pregnancy. To determine whether these abnormalities were the result of poor diabetes control, testosterone, androstenedione, human chorionic gonadotropin (HCG), and prolactin were studied longitudinally in diabetic women made normoglycemic before conception (N = 11) and normal (N = 6) control subjects beginning at the fifth week of gestation. HCG levels rose normally in all 11 diabetic and six control subjects and then declined as expected, with peak levels between 8 and 12 wk of gestation. Prolactin levels similarly rose significantly (P less than 0.00001) during the period studied. Plasma androstenedione did not increase during the course of this study, but testosterone levels increased significantly (P = 0.0001). Androgen levels were consistently higher in diabetic subjects despite the normoglycemic state, although the differences reached statistical significance at only one point. This study demonstrates that when normoglycemia is achieved before conception, HCG and prolactin are normal at 5 wk after the last menstrual period. The possibility that androgen levels may be higher in insulin-requiring diabetic women, perhaps due to peripheral hyperinsulinemia, should be explored.

Drug ingestion in a cohort of United States women proved consistently lower than in prior United States populations. Participating were 342 insulin-dependent diabetic and 387 control subjects who were enrolled before conception (76%) or no later than 21 days after conception (24%). Drug exposures were then recorded at entry and periodically throughout organogenesis (gestational weeks 6, 8, 10). During gestational weeks 1 to 10, approximately two thirds of the subjects were exposed to no agent other than oral iron, oral vitamins, or insulin (diabetic subjects). The mean exposures in gestational weeks 1 to 10 were 0.72 +/- 1.05 (SD) for diabetic women and 0.54 +/- 0.96 for control subjects; throughout pregnancy, the mean exposures were 1.26 +/- 1.66 and 1.58 +/- 1.78, respectively. The low exposure frequency in this contemporary United States population is highly encouraging. However, it follows that collaborative cohort efforts may be necessary in order to assess teratogenicity of drugs because relatively few women are now exposed.

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