Hair-relaxer use and risk of preterm birth among African-American women.

PURPOSE: To assess whether hair-relaxer use is associated with an increased risk of preterm birth among African-American women.
METHODS: We used data from the Black Women's Health Study. The participants were enrolled in 1995 and provided follow-up information in 1997, 1999, and 2001. Among 6130 singleton births reported by women <45 years of age during follow-up, 497 were preterm (<37 weeks gestation) because of premature rupture of membranes or spontaneous preterm labor for no known reason. In a case-control analysis, we compared the 497 preterm births with the 5633 births of longer gestation, and we used generalized estimation equation models to estimate multivariable odds ratios of preterm birth for users of hair relaxers.
RESULTS: With control for confounding factors, the odds ratio for preterm birth among ever users of hair relaxers relative to never users was 1.0 (95% confidence interval, 0.6-1.8). No elevations were seen in risk for use started at a young age or for frequent use for long durations.
CONCLUSIONS: These data suggest that hair-relaxer use does not play a role in the etiology of preterm birth in Black women.