title: Folic acid supplementation and dietary folate intake, and risk of preeclampsia.
abstract: OBJECTIVE
  Folic acid supplementation has been suggested to reduce the risk of preeclampsia. However, results from few epidemiologic studies have been inconclusive. We investigated the hypothesis that folic acid supplementation and dietary folate intake before conception and during pregnancy reduce the risk of preeclampsia.
  
  
  METHODS
  A birth cohort study was conducted in 2010-2012 at the Gansu Provincial Maternity & Child Care Hospital in Lanzhou, China. A total of 10,041 pregnant women without chronic hypertension or gestational hypertension were enrolled.
  
  
  RESULTS
  Compared with nonusers, folic acid supplement users had a reduced risk of preeclampsia (OR=0.61, 95% CI: 0.43-0.87). A significant dose-response of duration of use was observed among women who used folic acid supplemention during pregnancy only (P-trend=0.007). The reduced risk associated with folic acid supplement was similar for mild or severe preeclampsia and for early- or late-onset preeclampsia, although the statistical significant associations were only observed for mild (OR=0.50, 95% CI: 0.30-0.81) and late-onset (OR=0.60, 95% CI: 0.42-0.86) preeclampsia. The reduced risk associated with dietary folate intake during pregnancy was only seen for severe preeclampsia (OR=0.52, 95% CI: 0.31-0.87, for the highest quartile of dietary folate intake compared with the lowest).
  
  
  CONCLUSIONS
  Our study results suggest that folic acid supplementation and higher dietary folate intake during pregnancy reduce the risk of preeclampsia. Future studies are needed to confirm the associations.
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, CT, USA.
authors.forename: N
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: J
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: X
authors.initials: X
authors.lastname: He
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: M
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: H
authors.initials: H
authors.lastname: Cui
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: L
authors.initials: L
authors.lastname: Lv
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: X
authors.initials: X
authors.lastname: Lin
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: R
authors.initials: R
authors.lastname: Xu
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: D
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Dang
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: X
authors.initials: X
authors.lastname: Han
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: H
authors.initials: H
authors.lastname: Bai
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: R
authors.initials: R
authors.lastname: Lin
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: T
authors.initials: T
authors.lastname: Yao
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: J
authors.initials: J
authors.lastname: Su
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: B
authors.initials: B
authors.lastname: Ma
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: S
authors.initials: S
authors.lastname: Liu
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: W
authors.initials: W
authors.lastname: Qiu
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, CT, USA.
authors.forename: H
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, CT, USA.
authors.forename: J
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, Shanxi, China.
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Pediatrics, School of Medicine, Yale University, New Haven, CT, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Ehrenkranz
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Sciences, Bethesda, MD, USA.
authors.forename: C
authors.initials: C
authors.lastname: Kim
authors.affiliation: Gansu Provincial Maternity and Child Care Hospital, Lanzhou, Gansu, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, CT, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000328:Adult; D002681:China; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D006973:Hypertension / Q000517:prevention & control; D011225:Pre-Eclampsia / Q000517:prevention & control*; D011247:Pregnancy; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D014803:Vitamin B Complex; D005492:Folic Acid