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Luo K, Liu X, Zhou W, Nian M, Qiu W, Yang Y, Zhang J. Preconception exposure to perfluoroalkyl and polyfluoroalkyl substances and couple fecundity: A couple-based exploration. ENVIRONMENT INTERNATIONAL 2022; 170:107567. [PMID: 36240624 DOI: 10.1016/j.envint.2022.107567] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/09/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Numerous studies have examined the adverse health effects of perfluoroalkyl and polyfluoroalkyl substances (PFAS) but it remains unclear whether preconception exposure to PFAS affects couple fecundity. This prospective preconception cohort study with 936 Chinese couples aimed to comprehensively assess the effects of PFAS on couple fecundity [measured by the time to pregnancy (TTP)] and infertility (i.e., TTP > 12 menstrual cycles) with a focus on the effects of partner-specific exposure and joint-effects of couple-based exposure. Twenty-five PFAS were quantified in plasma from each partner, including seven branched isomers, two chlorinated polyfluoroalkyl ether sulfonic acids, four emerging PFAS replacements [i.e., 6:2 fluorotelomer phosphate diester (6:2 diPAP) and three short-chain alternatives: perfluoro-n-butanoicacid, perfluorobutane sulfonate and perfluoroheptanoic acid (PFHpA)]. Using a two-phase regression approach composed of elastic net regression and principal component analysis, we found that exposure to 6:2 diPAP and PFHpA rather than legacy PFAS in women and the couple-based exposure patterns characterized by high level of female 6:2 diPAP were significantly associated with reduced couple fecundity, which was independent of the adjustment of co-exposed PFAS homogenous from both partners. For example, a ln unit increase in female 6:2 diPAP was associated with 15 % [fecundity odds ratio (FOR) = 0.85, 95 %CI: 0.76, 0.96)] lower odds of couple fecundability (i.e., longer TTP) and 45 % increased risk of infertility [OR = 1.45 (95 %CI: 1.16, 1.81)], respectively. While most PFAS in men were not associated with couple fecundity, certain PFAS (e.g., perfluorohexane sulfonic acid) in men were negatively associated with infertility risk. However, the combined effects of PFAS mixture in couples were nonsignificant. Our findings suggest that PFAS in men and women may exert different impacts on couple fecundity. Preconception exposure to 6:2 diPAP and PFHpA in women may have the potential to impair couple fecundity.
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Affiliation(s)
- Kai Luo
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China; School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Xiaotu Liu
- School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
| | - Wei Zhou
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong 250012, China
| | - Min Nian
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China; School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Wei Qiu
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China; School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Yan Yang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China; Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory, Jieyang 515200, Guangdong, China; Synergy Innovation Institute of GDUT, Shantou 515041, China.
| | - Jun Zhang
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China; School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China.
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Bach C, Matthiesen N, Olsen J, Henriksen T. Conditioning on Parity in Studies of Perfluoroalkyl Acids and Time to Pregnancy: An Example from the Danish National Birth Cohort. ENVIRONMENTAL HEALTH PERSPECTIVES 2018; 126:117003. [PMID: 30417653 PMCID: PMC6371644 DOI: 10.1289/ehp1493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
BACKGROUND Previous studies have investigated the associations between perfluoroalkyl acids (PFAAs) in women and time to pregnancy (TTP). Inconsistent results may be explained by differences in conditioning on parity. OBJECTIVES We used causal directed acyclic graphs to illustrate potential confounding related to previous pregnancies and exposure measurement error due to differences in the interpregnancy interval in pregnancy-based studies that include parous women. We exemplified the potential importance of these issues using data from the Danish National Birth Cohort. METHODS We used discrete time survival models to estimate associations between maternal plasma PFAAs in early pregnancy and TTP in 638 nulliparous and 613 parous women. RESULTS PFAA quartiles were not associated with the TTP in nulliparous women. In parous women, higher PFAA quartiles were associated with longer TTP. The strongest associations were estimated for perfluorohexane sulfonate and perfluorooctane sulfonate. PFAA concentrations were higher in women with longer interpregnancy intervals. Accounting for the interpregnancy interval attenuated the estimated associations. CONCLUSIONS Associations between PFAAs and TTP in parous women may be biased by confounders related to previous pregnancies and exposure measurement error. To avoid these biases, studies that include parous women may need to condition on a) common causes of PFAAs and the TTP in the index pregnancy, b) previous births (a descendant of a collider), c) PFAA levels or common causes of PFAA levels and the TTP in the previous pregnancy (to alleviate collider stratification bias caused by conditioning on previous births), and d) the interpregnancy interval (in pregnancy-based studies). Alternatives would be to restrict studies to nulliparous women or to use toxicokinetic modeling to correct exposure estimates in parous women. These recommendations may be extended to studies of other chemicals with similar toxicokinetic properties. https://doi.org/10.1289/EHP1493.
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Affiliation(s)
- Cathrine Bach
- Department of Pediatrics and Adolescent Medicine, Viborg Regional Hospital, Viborg, Denmark
- Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
- Perinatal Epidemiology Research Unit, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Matthiesen
- Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
- Perinatal Epidemiology Research Unit, Aarhus University Hospital, Aarhus, Denmark
- Department of Pediatrics and Adolescent Medicine, Randers Regional Hospital, Randers, Denmark
| | - Jørn Olsen
- Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, USA
- Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
| | - Tine Henriksen
- Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
- Perinatal Epidemiology Research Unit, Aarhus University Hospital, Aarhus, Denmark
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