Common flame retardant chemicals are found in upholstered furniture, baby products, common consumer items – and also in human bodies across the world.

The organophosphate flame retardants (PFRs) levels found in the urine of women reduced the success rates of birth outcomes, according to a new study by Harvard researchers published in the journal Environmental Health Perspectives.

The 211 women undergoing in vitro fertilization at the Massachusetts General Hospital were assessed over the course of a decade, from 2005 to 2015. The women were all part of an investigation entitled the Environment and Reproductive Health, or EARTH, study – which attempted to assess lifestyle factors such as maternal age, race, smoking, body-mass index and other environmental characteristics on the ability to conceive and give birth.

The metabolites of three PFRs were detected in more than 80 percent of the women, they report. For those women with the highest concentrations of the derivatives of TDCIPP, TPHP, and mono-ITP, they had worse reproductive outcomes: 10 percent reduced chance of successful fertilization, 31 percent lower chance of embryo implantation, a 41 percent reduced chance of clinical pregnancy, and 38 percent decreased chances of live birth.

“These findings suggest that exposure to PFRs may be one of many risk factors for lower reproductive success,” said Courtney Carignan, first author, formerly a Harvard research fellow but now an assistant professor at Michigan State University.

“Couples undergoing IVF and trying to improve their chances of success by reducing their exposure to environmental chemicals may want to opt for products that are flame-retardant free,” said Russ Hauser, the senior author, acting chair of the Harvard T.H. Chan School of Public Health’s Department of Environmental Health.

Because of their hardy chemical nature, some flame retardants continue to pose risks to human health – even years after their use was curtailed by regulators. A group of flame retardants banned in the 1970s known as organochlorines still persist in the environment – and have been linked to some diagnoses on the autism spectrum.