title: Periconceptional intake of folic acid and food folate and risks of preterm delivery.
abstract: We investigated multiple sources of folate and folic acid to determine whether their periconceptional intakes were associated with preterm delivery. Studied were controls from the National Birth Defects Prevention Study delivered September 1998 to December 2005. Telephone interviews were conducted with 5952 (68% of eligible) mothers. Women were queried about intake of vitamin supplements in the 12 weeks before conception through delivery. A version of the Nurse's Health Study food frequency questionnaire was used to assess food sources. Eight percent of infants ( N = 487) were preterm (<37 weeks). Compared with women who began intake of supplements with folic acid before pregnancy, those who began any time during pregnancy had an ~20% lowered risk of preterm delivery. Lower dietary intakes showed a modest increased risk of preterm delivery: odds ratios were 1.44 (1.01 to 2.04) for lowest quartile intake of folate and 1.27 (0.95 to 1.69) for lowest quartile intake of folic acid compared with the highest. Findings suggest some evidence that folates influenced risks; however, an interpretation of results was also consistent with no association between intake of folates and preterm delivery.
authors.affiliation: Stanford University School of Medicine, Stanford, California, USA. gmshaw@stanford.edu
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
authors.forename: Suzan L
authors.initials: SL
authors.lastname: Carmichael
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Siega-Riz
mesh_terms: D000328:Adult; D001724:Birth Weight; D004032:Diet / Q000009:adverse effects*; D004034:Diet Surveys; D019587:Dietary Supplements / Q000009:adverse effects*; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000009:adverse effects*; D005865:Gestational Age; D006801:Humans; D007407:Interviews as Topic; D011247:Pregnancy; D047928:Premature Birth / Q000139:chemically induced / Q000453:epidemiology*; D012307:Risk Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D005492:Folic Acid