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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. [ABSTRACT FROM AUTHOR]

Uterine leiomyomata (UL) are the leading indication for hysterectomy in the United States. Dietary supplementation with lycopene was associated with reduced size and incidence of oviduct leiomyoma in the Japanese quail. Two US prospective cohort studies of women reported little association between intake of lycopene, or other carotenoids, and UL incidence. However, these studies relied on self-reported physician-diagnosed UL, which is prone to misclassification. This study examines the association between dietary intake of carotenoids and UL incidence. Data were derived from the Study of the Environment, Lifestyle, and Fibroids, a prospective cohort study. Women completed self-administered baseline questionnaires on demographic characteristics, reproductive history, and lifestyle, including a 110-item validated food frequency questionnaire, from which dietary intakes of carotenoids—including alpha carotene, beta carotene, cryptoxanthin, lutein-zeaxanthin, and lycopene—and vitamin A were estimated. One thousand two hundred thirty Black women aged 23 to 35 years who did not have a previous diagnosis of UL, cancer, or autoimmune disease were eligible for enrollment (2010-2012). Participants were residents of the Detroit, MI, metropolitan area. Transvaginal ultrasound was used to assess UL at baseline and 20, 40, and 60 months of follow-up. Cox regression was used to estimate hazard ratios and 95% CIs, adjusted for energy intake, age at menarche, education, body mass index, parity, age at first birth, years since last birth, current use of oral contraceptives or progestin-only injectables, alcohol intake, and cigarette smoking. Among 1,230 women without prevalent UL at baseline, 301 incident UL cases during follow-up were identified. Intakes of lycopene, other carotenoids, and vitamin A were not appreciably associated with UL incidence. Hazard ratios comparing quartiles 2 (2,376 to 3,397 μg/day), 3 (3,398 to 4,817 μg/day), and 4 (≥4,818 μg/day) with quartile 1 (<2,376 μg/day) of lycopene intake were 1.03 (95% CI 0.72 to 1.47), 1.22 (95% CI 0.86 to 1.72), and 0.95 (95% CI 0.67 to 1.36), respectively. Study findings do not support the hypothesis that greater carotenoid intake is associated with reduced UL incidence. [ABSTRACT FROM AUTHOR]

Uterine leiomyomata (UL) are associated with severe reproductive morbidity and are the primary indication for hysterectomy in the United States. A recent prospective cohort study of Black women reported positive associations between intakes of marine-sourced ω-3 fatty acids and UL risk. We examined whether intakes of dietary fat were associated with UL incidence in a 5-year prospective study of premenopausal Black women living in Detroit who underwent serial ultrasound. At baseline (2010–2012) and 20, 40, and 60 months of follow-up, participants underwent transvaginal ultrasound. Among 1,171 UL-free women at baseline, incident UL were detected in 277 women. Cox regression was used to estimate hazard ratios and 95% confidence intervals for the association of dietary fat and UL incidence. Intakes of total fat and saturated, monounsaturated, polyunsaturated, and trans -fat were not appreciably associated with UL incidence. Intake of the marine ω-3 polyunsaturated fatty acid, docosahexaenoic acid, was associated with 49% higher UL incidence (quartile 4 vs. 1: hazard ratio = 1.49, 95% confidence interval: 1.04, 2.14; P for trend = 0.01). Intakes of total marine ω-3 polyunsaturated fatty acids were similarly associated with elevated UL incidence (hazard ratio = 1.35, 95% confidence interval: 0.94, 1.93; P for trend = 0.03). It remains unclear whether the fatty acids or persistent environmental pollutants drive the association. [ABSTRACT FROM AUTHOR]