Second trimester folate status and preterm birth

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 weeksʹ 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 μg (SD ± 248). Intake ≤500 μg 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.