title: Paternal exposures to environmental chemicals and time-to-pregnancy: overview of results from the LIFE study.
abstract: Published findings from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study regarding the relation between environmental chemicals and couple fecundity, as measured by time-to-pregnancy (TTP), are reviewed with a particular focus on role of the male partner. The LIFE Study recruited 501 couples from 16 counties in two U.S. states upon discontinuing contraception for purposes of becoming pregnant. Upon enrollment, couples provided a blood and urine sample for the quantification of persistent and non-persistent environmental chemicals, respectively, and then completed daily journals until pregnant or up to one year of trying. Female partners used fertility monitors to aid the timing of intercourse relative to ovulation, and digital home pregnancy test kits on the day of expected menses. Chemical classes included: metals, persistent organic pollutants, environmental phenols, and phthalates that were quantified using inductively coupled plasma mass spectrometry or isotope dilution high-resolution or tandem mass spectrometry. Time-to-pregnancy (TTP) was defined as the number of prospectively observed menstrual cycles required for pregnancy. Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for each chemical and partner after adjusting for potential confounders and accounting for right censoring and time off contraception. FORs < 1 are suggestive of diminished fecundity or a longer TTP. Significant reductions (ranging from 17-31%) in couple fecundity were observed for male partners' concentration of lead (0.83; 0.70, 0.98), 2,2',4,4'-tetrahydroxybenzophenone (0.69; 0.49, 0.97), monobenzyl (0.80; 0.67, 0.97), and monomethyl (0.81; 0.70, 0.94) phthalates after adjusting for the female partners' concentrations. Seven PCB congeners quantified in men's serum were associated with a 17-29% reduction in couple fecundity. Our findings underscore the importance of a couple-based exposure design, inclusive of the male partner, when assessing couple-dependent outcomes such as TTP to avoid misinterpretation of results based only upon the female partner.
authors.affiliation: Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute for Child Health and Human Development, The National Institutes of Health, Rockville, MD, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Buck Louis
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Barr
authors.affiliation: Wadsworth Center, New York State Department of Health, Albany, NY, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kannan
authors.affiliation: Biostatistics and Bioinformatics Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute for Child Health and Human Development, The National Institutes of Health, Rockville, MD, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Biostatistics and Bioinformatics Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute for Child Health and Human Development, The National Institutes of Health, Rockville, MD, USA.
authors.forename: S
authors.initials: S
authors.lastname: Kim
authors.affiliation: Biostatistics and Bioinformatics Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute for Child Health and Human Development, The National Institutes of Health, Rockville, MD, USA.
authors.forename: R
authors.initials: R
authors.lastname: Sundaram
mesh_terms: D000293:Adolescent; D000328:Adult; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D018812:Paternal Exposure; D011247:Pregnancy; D061685:Time-to-Pregnancy; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants
keywords: endocrine disrupters; epidemiology; fecundity; men; time to pregnancy