title: Persistent organic pollutants exposure during pregnancy, maternal gestational weight gain, and birth outcomes in the mother-child cohort in Crete, Greece (RHEA study).
abstract: BACKGROUND
  Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and pesticides bioaccumulate through the food chain and cross the placenta. POPs are developmental toxicants in animals but the epidemiological evidence on pregnancy outcomes is inconsistent. Maternal gestational weight gain has been recently suggested as a key factor explaining the association between PCBs with lower birth weight.
  
  
  OBJECTIVE
  We examined whether in utero exposure to current low levels of different POPs is associated with fetal growth and gestational age in a mother-child cohort in Crete, Greece (Rhea study), and evaluated specifically whether maternal gestational weight gain may affect this association.
  
  
  METHODS
  We included 1117 mothers and their newborns from the Rhea study. Mothers were interviewed and blood samples collected during the first trimester of pregnancy. Information on birth outcomes was retrieved from medical records. Concentrations of several PCBs, other organochlorine compounds (dichlorodiphenyl dichloroethene [DDE], dichlorodiphenyl trichloroethane [DDT] and hexachlorobenzene [HCB]) and one polybrominated diphenyl ether congener (tetra-bromodiphenyl ether [BDE-47]), were determined in maternal serum by triple quadrupole mass spectrometry. Multiple linear regression models were used to investigate the associations of birth weight, gestational age, and head circumference with each compound individually on the log10 scale, and with combined exposures through the development of an exposure score.
  
  
  RESULTS
  In multivariate models, birth weight was negatively associated with increasing levels of HCB (β=-161.1g; 95% CI: -296.6, -25.7) and PCBs (β=-174.1g; 95% CI: -332.4, -15.9); after further adjustment for gestational weight gain these estimates were slightly reduced (β=-154.3g; 95% CI: -300.8, -7.9 for HCB and β=-135.7g; 95% CI: -315.4, 43.9 for PCBs). Furthermore, in stratified analysis, the association between POPs and birth weight was only observed in women with inadequate or excessive gestational weight gain. Small, negative associations were observed with head circumference while no association was observed with gestational age.
  
  
  CONCLUSIONS
  The findings suggest that prenatal exposure to PCBs and HCB impairs fetal growth and adds to the growing literature that demonstrates an association between low-level environmental pollutant exposure and fetal growth. Furthermore our results suggest that the association of POPs, maternal gestational weight gain and birth weight is probably more complex than that previously hypothesized.
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Hospital del Mar Research Institute (IMIM), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain; Department of Social Medicine, Faculty of Medicine, University of Crete, Heraklion, Greece. Electronic address: m.vafeiadi@med.uoc.gr.
authors.forename: Marina
authors.initials: M
authors.lastname: Vafeiadi
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Hospital del Mar Research Institute (IMIM), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
authors.forename: Martine
authors.initials: M
authors.lastname: Vrijheid
authors.affiliation: Department of Social Medicine, Faculty of Medicine, University of Crete, Heraklion, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Fthenou
authors.affiliation: Department of Social Medicine, Faculty of Medicine, University of Crete, Heraklion, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Chalkiadaki
authors.affiliation: Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland.
authors.forename: Panu
authors.initials: P
authors.lastname: Rantakokko
authors.affiliation: Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland.
authors.forename: Hannu
authors.initials: H
authors.lastname: Kiviranta
authors.affiliation: National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry and Biotechnology, Athens, Greece.
authors.forename: Soterios A
authors.initials: SA
authors.lastname: Kyrtopoulos
authors.affiliation: Department of Social Medicine, Faculty of Medicine, University of Crete, Heraklion, Greece.
authors.forename: Leda
authors.initials: L
authors.lastname: Chatzi
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Hospital del Mar Research Institute (IMIM), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain; National School of Public Health, Athens, Greece.
authors.forename: Manolis
authors.initials: M
authors.lastname: Kogevinas
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000187:drug effects; D015331:Cohort Studies; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood / Q000633:toxicity; D005260:Female; D047109:Fetal Development / Q000187:drug effects; D006115:Greece; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000097:blood / Q000633:toxicity; D007231:Infant, Newborn; D018811:Maternal Exposure; D011247:Pregnancy; D011256:Pregnancy Outcome; D015430:Weight Gain / Q000187:drug effects*
chemical_list: D004785:Environmental Pollutants; D006843:Hydrocarbons, Chlorinated
keywords: Birth outcomes; Cohort studies; Gestational weight gain; HCB; PCBs; Persistent organic pollutants