The Effect Of Folic Acid Intake On Preterm Birth,Low Birth Weight And Small Gestational Age During The Perinatal Period

Objectives To investigate the associations of the different periods of folic acid supplementation and the length of folic acid supplementation with preterm birth(PB),low birth weight(LBW)and small gestational age(SGA).To explore the associations of dietary folate intake(DFI)with PB,LBW and SGA.To examine the joint associations of folic acid supplementation(FAS)and DFI with PB,LBW and SGA.Methods The research data was from Lanzhou birth cohort study.The dynamic cohort study included all pregnancy women in Lanzhou region between 2010 and 2012.A baseline surveys(mainly included a pregnancy women general information questionnaire,semi-quantitative food frequency questionnaire,folic acid supplementation questionnaire and clinical data questionnaire on pregnancy outcomes)were carried out to find out the distributions of PB,LBW and SGA and their exposure factors’distribution.Pearson’s chi-square tests(χ~2)were used to compare selected characteristics between PB and term birth,between LBW and normal birth weight,between appropriate gestational age and SGA.Unconditional logistic regression models were used to estimate adjusted odds ratio(OR)and95%confidence interval(95%CI)for the single and joint associations of folic acid supplementation and dietary folate intake with PB,LBW and SGA.Results1.The status of folic acid intake(FAI)in this cohort studyAmong pregnant women who took FAS during pregnancy,2744(35%)pregnant women took before conception and during pregnancy,350(4%)pregnant women had only before conception and 4770(61%)pregnant women received only during pregnancy;Among pregnant women who took DFI,The average level of DFI was 205.4±19.8μg/d,the average level of DFI was 180.2±16.4μg/d before conception,and the average level of DFI was244.5±15.3μg/d during pregnancy.2.The effect of FAI on PB during the perinatal periodFAS was the protective factor for PB(OR:0.80,95%CI:0.68-0.94),moderate preterm birth(OR:0.92,95%CI:0.77-1.09),very preterm birth(OR:0.50,95%CI:0.36-0.69),spontaneous preterm birth(OR:0.77,95%CI:0.64-0.93),and spontaneous preterm birth with premature rupture of membrane(PROM)(OR:0.49,95%CI:0.33-0.73),and the risk of preterm birth,moderate preterm birth,very preterm birth,spontaneous preterm birth,and PROM decreased with the increasing duration of FAS respectively;High DFI were significantly associated with reduced risks of preterm birth,moderate preterm birth,very preterm birth,spontaneous preterm birth,all with significant dose-responses;The P-value of interaction on a multiplicative scale was<0.001.3.The effect of FAI on LBW during the perinatal periodFAS was the protective factor for LBW(OR:0.80,95%CI:0.66-0.97),term-LBW(OR:0.59,95%CI:0.41-0.85),multiparous-LBW(OR:0.72,95%CI:0.54-0.94),and the risk of LBW,term-LBW,multiparous-LBW decreased with the increasing duration of FAS respectively;The P-value of interaction on a multiplicative scale was 0.223.4.The effect of FAI on SGA during the perinatal periodFAS was the protective factor for SGA(OR:0.78,95%CI:0.65-0.94),term-SGA(OR:0.78,95%CI:0.64-0.96),multiparous-SGA(OR:0.60,95%CI:0.44-0.81),and the risk of SGA,term-SGA,multiparous-SGA decreased with the increasing duration of FAS respectively;and the P-value of interaction on a multiplicative scale was 0.249.Conclusions1.In Lanzhou,high DFI and FAS were significantly associated with reduced risks of PB,moderate preterm birth,very preterm birth,spontaneous preterm birth and spontaneous preterm birth without PROM,all with significant dose-responses.And the positive interaction on multiplicative scale were observed for preterm birth.In Lanzhou,we should advocate FAS and DFI to lower the incidence of LBW by various clinical subtypes.2.In Lanzhou,FAS was associated with an reduced risk of LBW,term-LBW and multiparous-LBW,those risk decreasing with increasing duration of FAS.And there was not interaction of FAS and DFI on LBW.In Lanzhou,we should advocate FAS to lower the incidence of LBW by various clinical subtypes.3.In Lanzhou,FAS is associated with an reduced risk of SGA,term-SGA and multiparous-SGA,those risk decreasing with increasing duration of FAS.And there was not interaction of FAS and DFI on SGA.In Lanzhou,we should advocate FAS to lower the incidence of SGA by various clinical subtypes.