title: Prenatal polychlorinated biphenyl exposure is associated with decreased gestational length but not birth weight: archived samples from the Child Health and Development Studies pregnancy cohort.
abstract: BACKGROUND
  Polychlorinated biphenyls (PCBs), known endocrine disruptors, were banned in 1979 but persist in the environment. Previous studies are inconsistent regarding prenatal exposure to PCBs and pregnancy outcomes. We investigated associations between prenatal exposure to PCBs and gestational length and birth weight.
  
  
  METHODS
  In a sample of 600 infants (born between 1960 and 1963) randomly selected from Child Health and Development Studies participants followed through adolescence we measured 11 PCB congeners in maternal post partum sera (within three days of delivery). Length of gestation was computed from the reported first day of the last menstrual period (LMP) and delivery date. Linear regression was used to estimate associations between PCB exposure and gestational age and birth weight, adjusting for potential confounders. PCBs were grouped according to hypothesized biological action (1b (sum of weak phenobarbital inducers), 2b (sum of limited dioxin activity), and 3 (sum of CYP1A and CYP2b inducers)) or degree of ortho- substitution (mono, di, tri). Secondary analyses examined associations between total PCB exposure and exposure to individual congeners.
  
  
  RESULTS
  Each unit increase in mono-ortho substituted PCBs was associated with a 0.30 week decrease (95% confidence interval (CI) -0.59, -0.016), corresponding to a 2.1 (95% CI -4.13, -0.11) day decrease in length of gestation. Similar associations were estimated for di-ortho substituted PCBs, (1.4 day decrease; (95% CI -2.9, 0.1)) and group 3 PCBs (0.84 day decrease; (95% CI -1.8, 0.11). We found similar associations in congener specific analyses and for the sum of congeners.
  
  
  CONCLUSIONS
  Our study provides new evidence that PCB exposure shortens length of gestation in humans. This may have public health implications for population exposures.
authors: Department of Epidemiology, Mailman School of Public Health, Columbia University, Room 1614, 722 West 168th St, New York, NY 10032, USA.
authors: Katrina L
authors: KL
authors: Kezios
authors: Xinhua
authors: X
authors: Liu
authors: Piera M
authors: PM
authors: Cirillio
authors: Olga I
authors: OI
authors: Kalantzi
authors: Yunzhu
authors: Y
authors: Wang
authors: Myrto X
authors: MX
authors: Petreas
authors: June-Soo
authors: JS
authors: Park
authors: Gary
authors: G
authors: Bradwin
authors: Barbara A
authors: BA
authors: Cohn
authors: Pam
authors: P
authors: Factor-Litvak
mesh_terms: D000293:Adolescent; D000328:Adult; D001724:Birth Weight / Q000187:drug effects*; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000032:analysis / Q000097:blood / Q000633:toxicity*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000097:blood / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced* / Q000453:epidemiology; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D013972:Thyrotropin; D011078:Polychlorinated Biphenyls; D013974:Thyroxine