title: Mendelian randomization analysis of the effect of maternal homocysteine during pregnancy, as represented by maternal MTHFR C677T genotype, on birth weight.
abstract: BACKGROUND
  We used Mendelian randomization analysis to investigate the causal relationship between maternal homocysteine level, as represented by maternal methylenetetrahydrofolate reductase (MTHFR) C677T genotype, with the birth weight of offspring.
  
  
  METHODS
  We recruited women at 24 to 28 weeks' gestation who visited Ewha Womans University Hospital for prenatal care during the period from August 2001 to December 2003. A total of 473 newborns with a gestational age of at least 37 weeks were analyzed in this study. We excluded twin births and children of women with a history of gestational diabetes, gestational hypertension, or chronic renal disease. The association of maternal homocysteine concentration with the birth weight of infants was analyzed using 2-stage regression.
  
  
  RESULTS
  MTHFR C677T genotype showed a dose-response association with homocysteine concentration for each additional T allele (Ptrend < 0.01). Birth weight decreased from 120 to 130 grams as maternal homocysteine level increased, while controlling for confounding factors; however, the association was of marginal significance (P = 0.06).
  
  
  CONCLUSIONS
  Our results suggest an adverse relationship between maternal homocysteine level and birth weight. A reduction in homocysteine levels might positively affect birth outcomes.
authors.affiliation: Department of Preventive Medicine, School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Hye Ah
authors.initials: HA
authors.lastname: Lee
authors.forename: Eun Ae
authors.initials: EA
authors.lastname: Park
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Cho
authors.forename: Hae Soon
authors.initials: HS
authors.lastname: Kim
authors.forename: Young Ju
authors.initials: YJ
authors.lastname: Kim
authors.forename: Hwayoung
authors.initials: H
authors.lastname: Lee
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Gwak
authors.forename: Ki Nam
authors.initials: KN
authors.lastname: Kim
authors.forename: Namsoo
authors.initials: N
authors.lastname: Chang
authors.forename: Eun Hee
authors.initials: EH
authors.lastname: Ha
authors.forename: Hyesook
authors.initials: H
authors.lastname: Park
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D057182:Mendelian Randomization Analysis; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D056910:Republic of Korea
chemical_list: D006710:Homocysteine; D042965:Methylenetetrahydrofolate Reductase (NADPH2)