Periconceptional vitamin use, dietary folate, and the occurrence of neural tube defects.
With a case-control study, we investigated whether periconceptional intake of supplemental or dietary folate reduced the risk of having a neural tube defect (NTD)-affected pregnancy. Mothers of 549 (88% of eligible) cases and 540 (88%) controls were interviewed in person about vitamin supplements used in either the 3 months before or the 3 months after conception and also about usual diet in the 3 months before conception. Women with any use of a folic acid-containing vitamin in the 3 months before conception had a lower risk of having an NTD-affected pregnancy [odds ratio (OR) = 0.65; 95% confidence interval (CI) = 0.45-0.94]. ORs were similar for 3 levels (< 0.4, 0.4-0.9, and > 0.9 mg per day) of average daily intake of folic acid. Any level of use in the first 3 months after conception resulted in a lowered risk as well (OR = 0.60; 95% CI = 0.46-0.79). Reduced risks were less marked for Hispanics and were not observed among women who graduated from college. Modest reduced risks were noted among non-vitamin users whose estimated daily dietary intake of folate was more than 0.227 mg. We observed decreasing risk with increasing folate intake from combined dietary sources and vitamin supplements. A reduction in NTD risk associated with folate intake is consistent with other studies; however, the reduced risk may be particular to subsets of the population, primarily non-Hispanic women and women whose education does not exceed high school.
Shaw
G M
GM
California Birth Defects Monitoring Program, Emeryville 94608, USA.
Schaffer
D
D
Velie
E M
EM
Morland
K
K
Harris
J A
JA
D000328:Adult; D002140:California / Q000453:epidemiology; D016022:Case-Control Studies; D003710:Demography; D004032:Diet; D002149:Energy Intake; D005006:Ethnicity; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D007231:Infant, Newborn; D007407:Interviews as Topic; D009436:Neural Tube Defects / Q000453:epidemiology / Q000208:ethnology / Q000517:prevention & control*; D016017:Odds Ratio; D016742:Preconception Care; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012307:Risk Factors; D014815:Vitamins / Q000008:administration & dosage / Q000627:therapeutic use*
D014815:Vitamins; D005492:Folic Acid