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

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 on 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 (FR) and 95% confidence intervals (CI). 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 age <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 non-monotonic. In this preconception cohort study, use of chemical hair straighteners was associated with slightly reduced fecundability.

Associations between use of chemical hair products and epigenetic age: Findings from the Sister Study

“…15,16,32 To our knowledge, this is the first study investigating the associations between the use of chemical hair product use and epigenetic age. Although the use of chemical hair products, particularly permanent dye and straighteners/relaxers, has been linked to the incidence of cancers and other adverse health outcomes, [5][6][7][8][9][10][11][12][13] our findings suggest that these relationships may not be primarily attributed to biological aging pathways captured by . P trend : P value for trend using Wald test on ordinal categories of frequency of hair product use.…”

“…Some hair products, such as permanent hair dyes and chemical straighteners or relaxers, may contain harmful chemicals. 1,2 The use of these products, along with exposure to the chemicals commonly found in them, has been associated with various health outcomes, [3][4][5][6][7][8][9][10] including a higher incidence of hormone-driven cancers in women. [11][12][13] The biological pathways linking chemical hair product use to age-related health outcomes are not fully understood.…”