Reproductive
Hair relaxer use and menstrual disturbances in a North American cohort Ruth Geller* Ruth Geller Amelia Wesselink Samantha Schildroth Tamarra James-Todd Nyia Noel Donna Baird Lauren Wise
Background: Use of hair relaxers (chemical straighteners) is associated with higher risks of hormonally mediated conditions, but its relation to menstrual function during adulthood has not been studied. We hypothesized that current and former use of hair relaxers would be associated with abnormal uterine bleeding (AUB) and dysmenorrhea.
Methods: We analyzed baseline data from Pregnancy Study Online (PRESTO), an internet-based preconception cohort study of North American pregnancy planners. We included 14,366 participants aged 21-39 years who enrolled during 2014-2024 and reported on their typical menstrual cycle characteristics during the past couple years when not using hormonal contraceptives. We queried details of lifetime hair relaxer use including age at first use, frequency per year, duration of use, number of burns, and the longest-used brand. We defined AUB as cycle length <24 or >38 days, flow ≥7 days, irregular cycles, and/or heavy flow (≥30 pads/tampons per menses). We defined dysmenorrhea as severe cramps requiring medication and bed rest. We used log-binomial regression to estimate prevalence ratios (PR) and 95% CIs for the associations of hair relaxer use with AUB and dysmenorrhea, adjusted for potential confounders.
Results: Overall, 2% of participants were current users and 10% were former users of hair relaxers; 75% of ever users initiated use before age 20 years. The frequencies of AUB and dysmenorrhea were 31% and 8%, respectively. Compared with never use of hair relaxers, PRs for current use were 1.16 (95% CI 1.00-1.33) for AUB and 1.30 (95% CI 0.94-1.80) for dysmenorrhea; former use was not strongly associated with either outcome. Compared with never use of hair relaxers, participants who reported ever experiencing burns had a higher prevalence of dysmenorrhea (1-4 burns: PR=1.42, 95% CI 1.04-1.93; ≥5 burns: PR=1.46, 95% CI 1.00-2.13).
Conclusion: Some measures of hair relaxer use were associated with a higher prevalence of menstrual disturbances.
