title: Effect of folic acid supplementation on preterm delivery and small for gestational age births: A systematic review and meta-analysis.
abstract: To investigate the effect of folic acid (FA) supplementation on the risks of preterm delivery (PTD) and small for gestational age births (SGA).
  
  
  
  Cohort studies were identified from MEDLINE, EMBASE, the Cochrane Library, CINAHL, and CBM from inception to January 2015.
  
  
  
  Healthy women who want to get pregnancy or being pregnant.
  
  
  
  PTD and SGA.
  
  
  
  The association of FA and PTD was significant when supplement initiated after pregnancy (RR=0.68, 95%CI, 0.52-0.90), whereas no effect was founded if the initiation time was before conception (RR=0.89, 95%CI, 0.80-1.01). The results for the association between FA supplementation and SGA showed significant protective effect: initiated before conception (RR=0.70, 95%CI, 0.57-0.85) and initiated after conception (RR=0.84, 95%CI, 0.81-0.89).
  
  
  
  Folic acid supplementation is associated with a significant reduction on the risk of PTD when initiated after conception. It can also protect fetus from SGA.
authors.affiliation: Beijing University of Chinese Medicine, Bei San Huan East Road, Chaoyang District, Beijing 100029, People's Republic of China; National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China; Graduate School of Peking Union Medical College, Dongdan San Tiao, Dongcheng District, Beijing 100730, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China; Graduate School of Peking Union Medical College, Dongdan San Tiao, Dongcheng District, Beijing 100730, People's Republic of China.
authors.forename: Xiaona
authors.initials: X
authors.lastname: Xin
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China; Graduate School of Peking Union Medical College, Dongdan San Tiao, Dongcheng District, Beijing 100730, People's Republic of China.
authors.forename: Dujia
authors.initials: D
authors.lastname: Liu
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China.
authors.forename: Zuoqi
authors.initials: Z
authors.lastname: Peng
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: He
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China.
authors.forename: Jihong
authors.initials: J
authors.lastname: Xu
authors.affiliation: National Research Institute for Family Planning, 12 Da Hui Temple Road, Haidian District, Beijing 100181, People's Republic of China; Graduate School of Peking Union Medical College, Dongdan San Tiao, Dongcheng District, Beijing 100730, People's Republic of China. Electronic address: maxupumc@163.com.
authors.forename: Xu
authors.initials: X
authors.lastname: Ma
mesh_terms: D015331:Cohort Studies; D019587:Dietary Supplements; D004334:Drug Administration Schedule; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000517:prevention & control*
chemical_list: D005492:Folic Acid
keywords: Folic acid; Preterm delivery; Small for gestational age