title: Pre-conceptional intake of folic acid supplements is inversely associated with risk of preterm birth and small-for-gestational-age birth: a prospective cohort study.
abstract: Associations of folic acid supplementation with risk of preterm birth (PTB) and small-for-gestational-age (SGA) birth were unclear for the Chinese populations. The aim of the present study was to investigate the associations in a large Chinese prospective cohort study: the Jiaxing Birth Cohort. In the Jiaxing Birth Cohort, 240 954 pregnant women visited local clinics or hospitals within their first trimester in Southeast China during 1999-2012. Information on anthropometric parameters, folic acid supplementation and other maternal characteristics were collected by in-person interviews during their first visit. Pregnancy outcomes were recorded during the follow-up of these participants. Multinomial logistic regression was used to examine the association of folic acid supplementation with pregnancy outcomes. The prevalence of folic acid supplementation was 24·9% in the cohort. The prevalence of PTB and SGA birth was 3·48 and 9·2%, respectively. Pre-conceptional folic acid supplementation was associated with 8% lower risk of PTB (relative risk (RR) 0·92; 95% CI 0·85, 1·00; P=0·04) and 19% lower risk of SGA birth (RR 0·81; 95% CI 0·70, 0·95; P=0·008), compared with non-users. Higher frequency of pre-conceptional folic acid use was associated with lower risk of PTB (P trend=0·032) and SGA birth (P trend=0·046). No significant association between post-conceptional initiation of folic acid supplementation and either outcome was observed. In conclusion, the present study suggests an association between pre-conceptional, but not post-conceptional, folic acid supplementation and lower risk of PTB and SGA birth in the Jiaxing Birth Cohort. Further research in other cohorts of large sample size is needed to replicate these findings.
authors.affiliation: 1Department of Food Science and Nutrition,Zhejiang University,Hangzhou,310058,People's Republic of China.
authors.forename: Ju-Sheng
authors.initials: JS
authors.lastname: Zheng
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Guan
authors.affiliation: 1Department of Food Science and Nutrition,Zhejiang University,Hangzhou,310058,People's Republic of China.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Xuejuan
authors.initials: X
authors.lastname: Tang
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Chen
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Meilong
authors.initials: M
authors.lastname: Xu
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Lingping
authors.initials: L
authors.lastname: Wu
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Shanlin
authors.initials: S
authors.lastname: Zhu
authors.affiliation: 3Jiaxing Maternity and Child Health Care Hospital,Jiaxing,314051,People's Republic of China.
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liu
authors.affiliation: 4Department of Nutrition,Harvard School of Public Health,Boston 02115,MA,USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.affiliation: 1Department of Food Science and Nutrition,Zhejiang University,Hangzhou,310058,People's Republic of China.
authors.forename: Duo
authors.initials: D
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002681:China; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005500:Follow-Up Studies; D006801:Humans; D007236:Infant, Small for Gestational Age; D016015:Logistic Models; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D047928:Premature Birth / Q000517:prevention & control*; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult
chemical_list: D005492:Folic Acid
keywords: Folic acid; LBW low birth weight; PTB preterm birth; Pregnancy; Preterm birth; Prospective cohorts; RR relative risk; SGA small-for-gestational-age; Small-for-gestational-age birth