Use of Chemical Hair Straighteners and Fecundability in a North American Preconception Cohort

• Published in: American journal of epidemiology Vol. 192; no. 7; pp. 1066 - 1080
• Main Authors: Wise, Lauren A, Wang, Tanran R, Ncube, Collette N, Lovett, Sharonda M, Abrams, Jasmine, Boynton-Jarrett, Renée, Koenig, Martha R, Geller, Ruth J, Wesselink, Amelia K, Coleman, Chad M, Hatch, Elizabeth E, James-Todd, Tamarra
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 07-07-2023; Oxford Publishing Limited (England)
• Subjects: Cohort analysis; Cohort Studies; Endocrine disruptors; Female; Fertility; Hair; Humans; North America; Original Contribution; Pregnancy; Prospective Studies; Questionnaires; Regression analysis; Regression models; Statistical analysis; Surveys and Questionnaires; North America; hair straighteners; females; endocrine-disrupting chemicals; fertility; prospective studies
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/aje/kwad079

Abstract
Chemical hair straighteners (“relaxers”) are used by millions of North Americans, particularly women of color. Hair relaxers may contain endocrine-disrupting compounds, which can harm fertility. We evaluated the association between hair relaxer use and fecundability among 11,274 participants from Pregnancy Study Online (PRESTO), a North American preconception cohort study. During 2014–2022, participants completed a baseline questionnaire in which they reported their history of relaxer use and completed follow-up questionnaires every 8 weeks for 12 months or until pregnancy, whichever came first. We used multivariable-adjusted proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs). Relative to never use, fecundability was lower among current (FR = 0.81, 95% CI: 0.64, 1.03) and former (FR = 0.89, 95% CI: 0.81, 0.98) users of hair relaxers. FRs for first use of hair relaxers at ages <10, 10–19, and ≥20 years were 0.73 (95% CI: 0.55, 0.96), 0.93 (95% CI: 0.83, 1.04), and 0.85 (95% CI: 0.74, 0.98), respectively. Fecundability was lowest among those with longer durations of use (≥10 years vs. never: FR = 0.71, 95% CI: 0.54, 0.91) and more frequent use (≥5 times/year vs. never: FR = 0.82, 95% CI: 0.60, 1.11), but associations were nonmonotonic. In this preconception cohort study, use of chemical hair straighteners was associated with slightly reduced fecundability.