Exposure to phthalates, a group of plasticizing and solvent chemicals found in many household products, was linked to a lower chance of pregnancy, but not pregnancy loss, according to research by an environmental and reproductive epidemiologist at the University of Massachusetts Amherst.
The study, published this week in the journal Environmental Health Perspectivesalso noted an association between preconception exposure to phthalates and changes in women’s reproductive hormones, as well as increased inflammation and oxidative stress.
“Phthalates are ubiquitous endocrine disruptors, and we are exposed to them every day,” says lead author Carrie Nobles, assistant professor of environmental health sciences in the School of Public Health and Health Sciences.
Phthalates are found in common products such as shampoo, makeup, vinyl flooring, toys and medical devices. People are exposed primarily by ingesting food and liquids that have come into contact with products containing the chemicals, according to a fact sheet from the Centers for Disease Control and Prevention.
Nobles and team analyzed data from a “unique cohort” of women in the preconception time-to-pregnancy study, known as EAGeR (Effects of Aspirin in Pregnancy and Reproduction), which evaluated the effect of low-dose aspirin in live birth rates. The study includes detailed information on 1,228 participants during six menstrual cycles when they were trying to get pregnant. Women who became pregnant were followed throughout pregnancy.
“We were able to look at certain environmental exposures like phthalates and how that relates to how long it takes to get pregnant. There was detailed data for each menstrual cycle, so we had a good handle on the date of ovulation and the time of pregnancy when that happened,” says Nobles.
The body breaks down phthalates into metabolites that are excreted in the urine and can be analyzed. The researchers measured 20 phthalate metabolites in urine samples taken when participants were enrolled in the study.
“We found that there were three maternal compounds that seemed to be most strongly associated with taking longer to get pregnant, although we saw a general trend toward taking longer to get pregnant across all the phthalates we looked at,” says Nobles. . “As the exposure increased, we saw more and more effect.”
The researchers also looked at a global marker of inflammation, C-reactive protein, and found that women who had higher levels of phthalate exposure also had higher levels of inflammation and oxidative stress, which can lead to organ and tissue damage and ultimately disease. .
In addition, women who showed higher levels of phthalates had lower estradiol and higher follicle-stimulating hormone during the menstrual cycle, which play an important role in ovulation and the early establishment of pregnancy.
“This profile — estradiol stays low and follicle-stimulating hormone stays high — is actually something we see in women who have ovarian failure, which can happen with age as well as some other factors,” she says. Nobles. “Ovulation just doesn’t happen as well as it used to.”
While women can check consumer product labels and look for phthalate-free options, the ubiquitous nature of the chemicals makes it difficult for an individual to control their exposure.
In Europe, some phthalates are banned or severely restricted in their use, but the US has no official bans. Nobles says the research findings add to the evidence that phthalate exposure has a negative impact on women’s reproductive health and can be used to help inform policy.
“Maybe we want to think differently about our regulatory system and how we identify significant exposures that have adverse effects on whether people can get pregnant and have a healthy pregnancy,” says Nobles.