Periconceptional nutrient intake and risk for neural tube defect-affected pregnancies

We investigated whether intakes of nutrients, including folate, by women in the periconceptional period were associated with risks of neural tube defe ct (NTD)-affected pregnancies. Data were part of a case-control study of fe tuses and infants with NTDs among 1989-1991 California births. We conducted interviews with mothers of 409 NTD cases and 420 nonmalformed controls. Nu trient intake for the 3 months before conception was derived from food freq uency questionnaires and from questions to mothers about vitamin/mineral su pplement use. We computed NTD risk for each nutrient controlling for the in fluence of all other studied nutrients and for maternal education, race/eth nicity, height, and prepregnancy weight. Most single nutrients reduced NTD risks when intakes were considered in quartiles and unadjusted for other nu trients. Some of the same nutrients, however, did not provide similar inter pretations when we adjusted for other nutrients. Adjusted analyses revealed decreased NTD risks with increased intakes of methionine, lutein, magnesiu m, zinc, and thiamin for women who did not use vitamin supplements periconc eptionally. We observed decreased NTD risks associated with increased intak es of linoleic acid, cysteine, calcium, and zinc for women who used supplem ents. We also observed increased NTD risks with increased intakes of oleic acid. For users as well as nonusers of vitamin supplements, we observed red uced risks with increased intakes of grains and dairy products. Chance was a likely alternative explanation for many of the observed risk patterns.