• Posted December 20, 2023

Phthalates, Found in Everyday Products, Might Lower Fertility

Exposure to a common chemical group found in many household products may delay or even prevent a woman from becoming pregnant, a new study says.

Phthalates can lower a woman's odds of becoming pregnant by up to 18% in any given month, researchers report in the journal Environmental Health Perspectives.

Phthalates are chemicals found in products like shampoo, makeup, soaps, hair sprays, toys, vinyl flooring and medical devices.

These chemicals are known “endocrine disruptors,” substances that can influence and alter the way hormones function in the human body.

“Phthalates are ubiquitous endocrine disruptors and we're exposed to them every day,” lead researcher Carrie Nobles said in a news release. She's an assistant professor of environmental health sciences in the University of Massachusetts Amherst School of Public Health and Health Sciences.

For their study, Nobles and her colleagues analyzed data on more than 1,200 women who were followed through six menstrual cycles as they attempted to get pregnant, as part of previous research on the effect of low-dose aspirin on birth rates.

“We were able to look at some environmental exposures like phthalates and how that relates to how long it takes to get pregnant,” Nobles said. “There was detailed data for each menstrual cycle, so we had a good handle on the date of ovulation and the timing of pregnancy when that happened.”

The body breaks phthalates down into simpler substances called metabolites that are excreted in urine, giving researchers a chance to track phthalate levels in a person's body.

The research team looked at 20 specific phthalate metabolites found in the women's bodies.

“We saw a general trend toward it taking longer to get pregnant across the phthalates we looked at,” Nobles said. “As exposure got higher, we saw more and more of an effect.”

They also identified three specific compounds that were most strongly associated with taking longer to get pregnant, Nobles said.

Mono-(2-ethylhexyl) phthalate was associated with a 12% lower chance of getting pregnant during a monthly cycle; mono-benzyl phthalate with a 15% lower chance; and mono-butyl phthalate with an 18% lower chance.

Researchers also found that women with higher levels of exposure had higher levels of inflammation, which could affect their ability to get pregnant.

Women with high phthalate levels also had lower levels of the female hormone estradiol and higher levels of follicle-stimulating hormone across their menstrual cycles, researchers said. Both hormones play an important role in ovulation and the early establishment of pregnancy.

“This profile -- estradiol staying low and follicle-stimulating hormone staying high -- is actually something that we see in women who have ovarian insufficiency, which can happen with age as well as due to some other factors,” Nobles said. “Ovulation just isn't happening as well as it used to.”

Women can read consumer product labels and look for phthalate-free options, but the chemicals are everywhere in the environment and hard to avoid.

People are typically exposed to phthalates by eating and drinking foods that have contacted products containing the chemicals, according to the U.S. Centers for Disease Control and Prevention (CDC).

European countries ban or severely restrict the use of certain phthalates, researchers noted, but the U.S. has no formal prohibitions on their use.

These findings add to the evidence that phthalate exposure has a negative effect on women's reproductive health, Nobles said.

“Maybe we want to think differently about our regulatory system and how we identify important exposures that are having adverse effects on whether people can get pregnant and have a healthy pregnancy,” she said.

More information

The U.S. Centers for Disease Control and Prevention has more about phthalates.

SOURCE: University of Massachusetts Amherst, news release, Dec. 13, 2023

What This Means For You

Women trying to get pregnant should consider limiting their exposure to phthalates, if possible.