Second trimester folate status and preterm birth

Am J Obstet Gynecol. 2004 Dec;191(6):1851-7. doi: 10.1016/j.ajog.2004.07.076.


Objective: The purpose of this study was to show that maternal folate status during pregnancy may be related to preterm birth.

Study design: 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.

Conclusion: These results support the hypothesis that low folate levels during the second trimester of pregnancy are associated with an increased risk of preterm birth.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Analysis of Variance
  • Blood Chemical Analysis
  • Chi-Square Distribution
  • Cohort Studies
  • Dietary Supplements*
  • Female
  • Folic Acid / blood
  • Folic Acid / metabolism*
  • Folic Acid Deficiency / complications*
  • Folic Acid Deficiency / diagnosis*
  • Follow-Up Studies
  • Humans
  • Linear Models
  • Maternal Nutritional Physiological Phenomena
  • Nutritional Requirements
  • Pregnancy
  • Pregnancy Trimester, Second
  • Premature Birth / etiology*
  • Premature Birth / prevention & control
  • Prenatal Care
  • Prospective Studies
  • Risk Assessment


  • Folic Acid