NEURAL-TUBE DEFECTS AND MATERNAL SERUM ZINC AND COPPER CONCENTRATIONSIN MID-PREGNANCY - A CASE-CONTROL STUDY

Objective: To assess the relationship between mid-pregnancy maternal s erum zinc and copper and neural tube concentrations defects. Design: A prospective case-control study during 1978-1988 within a statewide ho spital-based neural tube defect screening program measuring maternal s erum a-fetoprotein levels at mid-pregnancy. Subjects: Cases were 69 wo men with fetuses with confirmed neural tube defects. Controls were 592 women with fetuses without neural tube defects who were individually matched to cases for hospital, calendar date of screening, age and par ity; there was a variable control-to-case ratio. Results: For both unm atched and adjusted matched analyses, mean maternal serum zinc concent ration was higher in cases than controls (P = 0.02 and P = 0.03, respe ctively). There were no case-control differences for serum copper conc entrations. Conditional logistic regression analysis showed a (statist ically non-significant) increase in risk of neural defects in women wh ose serum zinc concentration was more than two standard deviations abo ve the population mean. Conclusion: Within the normal range of materna l serum zinc and copper concentrations there is no variation in risk o f neural tube defects. However, women with very high serum zinc levels may have an increased risk of neural tube defects. This could reflect deficient maternal-to-fetal transfer of zinc in some of those individ uals. Any such phenomenon would be manifest in observational, but not experimental, studies.