title: Maternal smoking is associated with decreased 5-methyltetrahydrofolate in cord plasma.
abstract: BACKGROUND
  Maternal-fetal folate transport via the placenta has been shown to be concentrative. Exposure to cigarette smoke is associated with decreased maternal folate status through altered dietary intakes and possibly through nondietary mechanisms such as increased folate turnover. The effect of maternal smoking on fetal folate status has not been documented.
  
  
  OBJECTIVE
  The objective was to determine the effect of maternal smoking on plasma 5-methyltetrahydrofolic acid (5-MTHFA) concentrations in umbilical cord blood.
  
  
  METHODS
  African American women were recruited from an antenatal clinic in Detroit, MI. Plasma 5-MTHFA concentrations were measured in maternal-umbilical cord pairings (n = 58). The participants completed a structured interview to determine demographic characteristics, including smoking.
  
  
  RESULTS
  Concentrations of 5-MTHFA were significantly higher in venous cord plasma (16.8 +/- 7.5 ng/mL) than in maternal plasma (13.0 +/- 7.5 ng/mL) but remained associated (r = 0.60, P < 0.001) with each other. Cigarettes smoked by the mothers was negatively associated (r = -0.31, P = 0.019) with venous cord 5-MTHFA concentrations and remained so after control for maternal plasma 5-MTHFA and other variables. Venous cord plasma 5-MTHFA was significantly lower in smoking (15.1 +/- 7.6 ng/mL; n = 32) than in nonsmoking (19.0 +/- 7.0 ng/mL; n = 26) mothers.
  
  
  CONCLUSIONS
  Cord plasma 5-MTHFA concentrations were elevated relative to maternal blood, as expected, because the placenta is capable of concentrative folate transport to the fetus. The negative effect of maternal smoking on infant, but not on maternal, 5-MTHFA status indicates that maternal smoking may impair folate transport to the fetus.
authors.affiliation: Laboratory of Nutritional and Nutraceutical Research, Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada. kstark@uwaterloo.ca
authors.forename: Ken D
authors.initials: KD
authors.lastname: Stark
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Pawlosky
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Sokol
authors.forename: John H
authors.initials: JH
authors.lastname: Hannigan
authors.forename: Norman
authors.initials: N
authors.lastname: Salem
mesh_terms: D001741:Black or African American; D001827:Body Height; D001835:Body Weight; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood; D012907:Smoking / Q000097:blood*; D013763:Tetrahydrofolates / Q000097:blood* / Q000172:deficiency*; D014469:Umbilical Arteries; D014471:Umbilical Veins
chemical_list: D013763:Tetrahydrofolates; C013123:5,10-methylenetetrahydrofolic acid