title: Second trimester folate status and preterm birth.
abstract: OBJECTIVE
  The purpose of this study was to show that maternal folate status during pregnancy may be related to preterm birth.
  
  
  METHODS
  Women were recruited at 24 to 29 weeks' gestation from 1995 to 2000 into the Pregnancy, Infection, and Nutrition Study. Those who completed an interview and a food frequency questionnaire, or provided a blood sample for radioassay of serum (n = 2026) and red blood cell (n = 1034) folate were included.
  
  
  RESULTS
  Mean daily dietary folate intake was 463 microg (SD +/- 248). Intake </=500 microg was associated with increased preterm delivery (RR = 1.8, 95% CI 1.4-2.6) controlling for total energy intake. Serum folate levels <16.3 ng/mL and red blood cell folate levels </=626.6 ng/mL yielded adjusted risk ratios of 1.8 (95% CI 1.3-2.5) and 1.7 (95% CI 1.1-2.6), respectively. Patterns were similar for spontaneous and overall preterm birth.
  
  
  CONCLUSIONS
  These results support the hypothesis that low folate levels during the second trimester of pregnancy are associated with an increased risk of preterm birth.
authors.affiliation: Carolina Population Center, CB # 8120 University Square, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516-3997, USA. am_siegariz@unc.edu
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Siega-Riz
authors.forename: David A
authors.initials: DA
authors.lastname: Savitz
authors.forename: Steven H
authors.initials: SH
authors.lastname: Zeisel
authors.forename: John M
authors.initials: JM
authors.lastname: Thorp
authors.forename: Amy
authors.initials: A
authors.lastname: Herring
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001774:Blood Chemical Analysis; D016009:Chi-Square Distribution; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000097:blood / Q000378:metabolism*; D005494:Folic Acid Deficiency / Q000150:complications* / Q000175:diagnosis*; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D039382:Maternal Nutritional Physiological Phenomena; D009751:Nutritional Requirements; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D047928:Premature Birth / Q000209:etiology* / Q000517:prevention & control; D011295:Prenatal Care; D011446:Prospective Studies; D018570:Risk Assessment
chemical_list: D005492:Folic Acid