Research Indicates Exposure to Household Chemicals May Reduce the Likelihood of Conceiving


December 15, 2023
University of Massachusetts Amherst
Exposure to phthalates, a group of plasticizing and solvent chemicals found in many household products, was linked to a lower probability of getting pregnant, but not to pregnancy loss, according to research by environmental and reproductive epidemiologists.

Exposure to phthalates, a group of plasticizing and solvent chemicals commonly found in various household products, has been associated with a reduced likelihood of conception, although no link was found to pregnancy loss. This conclusion stems from research conducted by an environmental and reproductive epidemiologist at the University of Massachusetts Amherst.

Published this week in the journal Environmental Health Perspectives, the study also highlighted a connection between exposure to phthalates before conception and alterations in women's reproductive hormones. Additionally, it noted an increase in inflammation and oxidative stress associated with this exposure.
"Phthalates are ubiquitous endocrine disruptors, and we're 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.

These chemicals, found in common products like shampoo, makeup, vinyl flooring, toys, and medical devices, are encountered through ingestion of food and liquid that has come into contact with items containing phthalates, as noted by a Centers for Disease Control and Prevention fact sheet.

Nobles and her team conducted an analysis using data from a distinctive group of women participating in the preconception time-to-pregnancy study called EAGeR (Effects of Aspirin in Gestation and Reproduction). This study, which examined the impact of low-dose aspirin on live-birth rates, provided detailed information on 1,228 participants during six menstrual cycles as they attempted to conceive. The women who became pregnant were then followed throughout their pregnancies.
"We were able to examine environmental exposures like phthalates and their connection to the time it takes to conceive. With detailed data for each menstrual cycle, we had a good understanding of ovulation dates and pregnancy timing," says Nobles.

Phthalates are broken down by the body into metabolites that are excreted in urine and can be analyzed. The researchers assessed 20 phthalate metabolites in urine samples collected when participants joined the study.

"We identified three parent compounds that showed a strong association with an extended time to conceive, although we observed a general trend of increased time to conceive across the various phthalates we examined," Nobles explains. "As exposure levels rose, we noted a more pronounced effect."
The study also investigated a global marker of inflammation, C-reactive protein, and observed that women with higher levels of phthalate exposure exhibited elevated levels of inflammation and oxidative stress. This heightened inflammation and oxidative stress can contribute to organ and tissue damage, ultimately increasing the risk of disease.

Furthermore, women with higher phthalate levels displayed lower estradiol and higher follicle-stimulating hormone levels throughout the menstrual cycle. These hormones play crucial roles in ovulation and the early stages of pregnancy establishment.
"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," notes Nobles.

While women can make efforts to choose consumer products labeled as phthalate-free, the widespread use of these chemicals makes it challenging for individuals to fully control their exposure.

In Europe, specific phthalates are either banned or heavily restricted in use, but the United States lacks formal prohibitions.

Nobles emphasizes that these research findings contribute to the growing evidence that phthalate exposures have adverse effects on women's reproductive health. This information can be valuable in shaping policies and regulations.

"Perhaps we need to reconsider our regulatory system and how we identify significant exposures that adversely affect people's ability to conceive and have a healthy pregnancy," Nobles suggests.