title: Maternal Serum 25-Hydroxyvitamin D Concentrations during Pregnancy and Infant Birthweight for Gestational Age: a Three-Cohort Study.
abstract: BACKGROUND
  In response to inconsistent findings, we investigated associations between maternal serum 25-hydroxyvitamin D [25(OH)D] concentrations and infant birthweight for gestational age (BW/GA), including potential effect modification by maternal race/ethnicity and infant sex.
  
  
  METHODS
  Data from 2558 pregnant women were combined in a nested case-control study (preterm and term) sampled from three cohorts: the Omega study, the Pregnancy, Infection and Nutrition study, and the Pregnancy Outcomes and Community Health study. Maternal 25(OH)D concentrations were sampled at 4 to 29 weeks gestation (80% 14-26 weeks). BW/GA was modelled as sex and gestational age-specific birthweight z-scores. General linear regression models (adjusting for age, education, parity, pre-pregnancy body mass index, season at blood draw, and smoking) assessed 25(OH)D concentrations in relation to BW/GA.
  
  
  RESULTS
  Among non-Hispanic Black women, the positive association between 25(OH)D concentrations and BW/GA was of similar magnitude in pregnancies with female or male infants [beta (β) = 0.015, standard error (SE) = 0.007, P = 0.025; β = 0.018, SE = 0.006, P = 0.003, respectively]. Among non-Hispanic White women, 25(OH)D-BW/GA association was observed only with male infants, and the effect size was lower (β = 0.008, SE = 0.003, P = 0.02).
  
  
  CONCLUSIONS
  Maternal serum concentrations of 25(OH)D in early and mid-pregnancy were positively associated with BW/GA among non-Hispanic Black male and female infants and non-Hispanic White male infants. Effect modification by race/ethnicity may be due, in part, to overall lower concentrations of 25(OH)D in non-Hispanic Blacks. Reasons for effect modification by infant sex remain unclear.
authors.affiliation: Department of Epidemiology and Biostatistics, College of Human Medicine, Michigan State University, East Lansing, MI.
authors.forename: Yan
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Department of Epidemiology and Biostatistics, College of Human Medicine, Michigan State University, East Lansing, MI.
authors.forename: Claudia
authors.initials: C
authors.lastname: Holzman
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, the Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Siega-Riz
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, the Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors.forename: Nancy
authors.initials: N
authors.lastname: Dole
authors.affiliation: Department of Epidemiology, University of Washington, Seattle, WA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Enquobahrie
authors.affiliation: Maternal and Infant Health Branch, Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Cynthia D
authors.initials: CD
authors.lastname: Ferre
mesh_terms: D000328:Adult; D001741:Black or African American / Q000208:ethnology; D001724:Birth Weight / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000502:physiology; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012621:Seasons; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism; D044465:White People / Q000208:ethnology; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-hydroxyvitamin D; birthweight for gestational age; pregnancy; race/ethnicity; sex difference