Chemical hair straighteners, or relaxers, most often used by Latino, Black and mixed-race individuals, may affect fertility, according to new research led by the Boston University School of Public Health (BUSPH).

Published in the American Journal of Epidemiology, the study is among the first to link hair relaxers to a slight decrease in a person’s ability to conceive, a BUSPH news release said.

Because Latino, Black and mix-raced individuals use relaxers more often than other racial groups, they are more likely to be exposed to toxic chemicals and experience sustained scalp burns from the hair products, which the study found were associated with lower chances of conceiving.

Researchers emphasized that the societal pressure women of color face to conform to Eurocentric beauty norms as well as bans on certain Afrocentric hairstyles in some workplaces contribute to their disproportionate use of such toxic beauty products.

This study adds to an increasing body of research that links toxic, endocrine-disrupting chemicals found in beauty products to reproductive health issues. Researchers note that while chemicals such as phthalates, parabens and phenols may contribute to a decrease in the ability to conceive, many ingredients are often left off of product labels and, therefore, further research is required to better understand which specific chemicals may impact fertility.

“Our work underscores the importance of expanding research on the reproductive health effects of beauty product use to promote environmental justice and increase health equity,” said study lead author Lauren Wise, ScD, professor of epidemiology at BUSPH, in the news release.

The study analyzed survey data from the BUSPH-based Pregnancy Study Online (PRESTO). The ongoing study involves participants from the United States and Canada who are planning to become pregnant and follows them from preconception through six months postdelivery. Researchers analyzed information on several aspects of hair relaxer use from 11,274 participants during 2014 to 2022.

The data showed that individuals who reported ever using relaxers were more likely to be residents of the Southern United States, older and unmarried; more likely to have less education and a lower annual income and a higher BMI; and more likely to smoke and experience longer periods of time trying to become pregnant compared with those who never used relaxers.

Current and former use of hair relaxers was highest among Black participants, followed by Latino participants. Indeed, more than half of Black participants reported first using a hair relaxer before age 10.

To learn more about the impact of toxic hair straightening chemicals, read “Hairdressers of Color Exposed to Harmful Mix of Chemicals,” “Hair Relaxers Linked to Higher Risk for Uterine Cancer” and “Hair and Health.”