title: Preconception homocysteine and B vitamin status and birth outcomes in Chinese women.
abstract: BACKGROUND
  The associations between homocysteine, B vitamin status, and pregnancy outcomes have not been examined prospectively.
  
  
  OBJECTIVE
  We assessed the associations of preconception homocysteine and B vitamin status with preterm birth and birth of low-birth-weight (LBW) and small-for-gestational-age (SGA) infants in Chinese women.
  
  
  METHODS
  This was a case-control study of women aged 21-34 y. Preterm cases (n = 29) delivered living infants at <37 wk gestation; term controls (n = 405) delivered infants at > or =37 wk. LBW cases (n = 33) had infants weighing <2500 g; normal-birth-weight controls (n = 390) had infants weighing > or =2500 g. SGA cases (n = 65) had infants below the 10th percentile of weight-for-gestational-age; appropriate-for-gestational-age controls (n = 358) had infants above this cutoff. Nonfasting plasma concentrations of homocysteine, folate, and vitamins B-6 and B-12 were measured before conception.
  
  
  RESULTS
  Elevated homocysteine (> or =12.4 micro mol/L) was associated with a nearly 4-fold higher risk of preterm birth (OR: 3.6; 95% CI: 1.3, 10.0; P < 0.05). The risk of preterm birth was 60% lower among women with vitamin B-12 > or =258 pmol/L than among vitamin B-12-deficient women (OR: 0.4; 95% CI: 0.2, 0.9; P < 0.05) and was 50% lower among women with vitamin B-6 > or =30 nmol/L than among vitamin B-6-deficient women (OR: 0.5; 95% CI: 0.2, 1.2; NS). Folate status was not associated with preterm birth, and homocysteine and B vitamin status were not associated with LBW or SGA status.
  
  
  CONCLUSIONS
  Elevated homocysteine and suboptimal vitamin B-12 and B-6 status may increase the risk of preterm birth. These results need to be confirmed in larger prospective studies.
authors.affiliation: Departments of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA. ronnenberg@attbi.com
authors.forename: Alayne G
authors.initials: AG
authors.lastname: Ronnenberg
authors.forename: Marlene B
authors.initials: MB
authors.lastname: Goldman
authors.forename: Dafang
authors.initials: D
authors.lastname: Chen
authors.forename: Iain W
authors.initials: IW
authors.lastname: Aitken
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Jacob
authors.initials: J
authors.lastname: Selhub
authors.forename: Xiping
authors.initials: X
authors.lastname: Xu
mesh_terms: D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D005260:Female; D005492:Folic Acid / Q000097:blood; D005865:Gestational Age; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007236:Infant, Small for Gestational Age; D009752:Nutritional Status; D007752:Obstetric Labor, Premature / Q000453:epidemiology* / Q000209:etiology; D016742:Preconception Care; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012307:Risk Factors; D014805:Vitamin B 12 / Q000097:blood; D025101:Vitamin B 6 / Q000097:blood; D014803:Vitamin B Complex / Q000097:blood*; D014804:Vitamin B Deficiency / Q000150:complications / Q000453:epidemiology
chemical_list: D006710:Homocysteine; D014803:Vitamin B Complex; D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12