title: Phenols and parabens in relation to reproductive and thyroid hormones in pregnant women.
abstract: BACKGROUND
  Phenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies and limited human data suggest they may be endocrine disruptors. In the current study, we examined associations of phenols and parabens with reproductive and thyroid hormones in 106 pregnant women recruited for the prospective cohort, "Puerto Rico Testsite for Exploring Contamination Threats (PROTECT)".
  
  
  METHODS
  Urinary exposure biomarkers (bisphenol A, triclosan, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, butyl, methyl and propyl paraben) and serum hormone levels (estradiol, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone) were measured at up to two time points during pregnancy (16-20 weeks and 24-28 weeks). We used linear mixed models to assess relationships between exposure biomarkers and hormone levels across pregnancy, controlling for urinary specific gravity, maternal age, BMI and education. In sensitivity analyses, we evaluated cross-sectional relationships between exposure and hormone levels stratified by study visit using linear regression.
  
  
  RESULTS
  An IQR increase in methyl paraben was associated with a 7.70% increase (95% CI 1.50, 13.90) in SHBG. Furthermore, an IQR increase in butyl paraben as associated with an 8.46% decrease (95% CI 16.92, 0.00) in estradiol, as well as a 9.34% decrease (95% CI -18.31,-0.38) in estradiol/progesterone. Conversely, an IQR increase in butyl paraben was associated with a 5.64% increase (95% CI 1.26, 10.02) in FT4. Progesterone was consistently negatively associated with phenols, but none reached statistical significance. After stratification, methyl and propyl paraben were suggestively negatively associated with estradiol at the first time point (16-20 weeks), and suggestively positively associated with estradiol at the second time point (24-28 weeks).
  
  
  CONCLUSIONS
  Within this ongoing birth cohort, certain phenols and parabens were associated with altered reproductive and thyroid hormone levels during pregnancy. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required.
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Amira M
authors.initials: AM
authors.lastname: Aker
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Watkins
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Johns
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Kelly K
authors.initials: KK
authors.lastname: Ferguson
authors.affiliation: Department of Medicine, Georgetown University, 3900 Reservoir Rd NW, Washington, DC 20007, USA.
authors.forename: Offie P
authors.initials: OP
authors.lastname: Soldin
authors.affiliation: University of Puerto Rico Graduate School of Public Health, UPR Medical Sciences Campus, PO Box 365067, San Juan, PR 00936-5067, USA.
authors.forename: Liza V
authors.initials: LV
authors.lastname: Anzalota Del Toro
authors.affiliation: College of Engineering, Northeastern University, 110 Forsyth St, Boston, MA 02115, USA.
authors.forename: Akram N
authors.initials: AN
authors.lastname: Alshawabkeh
authors.affiliation: University of Puerto Rico Graduate School of Public Health, UPR Medical Sciences Campus, PO Box 365067, San Juan, PR 00936-5067, USA.
authors.forename: José F
authors.initials: JF
authors.lastname: Cordero
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA. Electronic address: meekerj@umich.edu.
authors.forename: John D
authors.initials: JD
authors.lastname: Meeker
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000652:urine; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006728:Hormones / Q000097:blood*; D006801:Humans; D010226:Parabens / Q000032:analysis*; D010636:Phenols / Q000652:urine*; D011247:Pregnancy; D011446:Prospective Studies; D011647:Puerto Rico; D055815:Young Adult
chemical_list: D015415:Biomarkers; D004785:Environmental Pollutants; D006728:Hormones; D010226:Parabens; D010636:Phenols
keywords: Parabens; Phenols; Pregnancy; Reproductive hormones; Thyroid hormones