Folic acid supplementation, dietary folate intake and risk of small for gestational age in China.

Objective: To investigate the hypothesis that folic acid supplementation and dietary folate intake before conception and during pregnancy reduce the risk of small for gestational age (SGA) and to examine the joint effect of folic acid supplementation and dietary folate intake on the risk of SGA. Design: Participants were interviewed by trained study interviewers using a standardized and structured questionnaire. Information on birth outcomes and maternal complications was abstracted from medical records and dietary information was collected via a semi-quantitative FFQ before conception and during pregnancy. Setting: A birth cohort data analysis using the 2010-2012 Gansu Provincial Maternity and Child Care Hospital. Participants: Women (n8758) and their children enrolled in the study. Results: Folic acid supplementation was associated with a reduced risk of SGA (OR = 0 center dot 72, 95 % CI 0 center dot 60, 0 center dot 86), with the reduced risk seen mainly for SGA at >= 37 weeks of gestational age (OR = 0 center dot 70, 95 % CI 0 center dot 58, 0 center dot 85) and nulliparous SGA (OR = 0 center dot 67, 95 % CI 0 center dot 54, 0 center dot 84). There was no significant association between dietary folate intake and SGA risk. Conclusions: Our study suggested that folic acid supplementation was associated with a reduced risk of SGA and the risk varied by preterm status and parity.