Exposure to Synthesized Chemicals Associated with Poorer Embryo Quality During IVF

ALBANY, N.Y. (Mar. 1, 2023) – A recent study from an international team shows that those who were exposed to higher amounts of perfluoroalkyl acids (PFAA)—a type of synthetic chemical—during in vitro fertilization (IVF) had poorer embryo quality than those who had lower amounts of exposure. This means that exposure to these chemicals may lower IVF success rates.

PFAA have been used since the 1940s in household products such as nonstick pans and food packaging. They get into the human body through dietary exposure, inhalation, and drinking water contamination, and previous research suggests that PFAA may negatively impact human reproductive health.

The team for this study, comprised of researchers from Sun Yat-sen University, the University at Albany, George Mason University, Leiden University Medical Center, and the People's Hospital of Guangxi Zhuang Autonomous Region, examined the PFAA in the follicular fluid that surrounds the developing egg cell from women undergoing IVF to see if there was a relationship between PFAA amount and egg quality. Shao Lin, one of the paper’s corresponding authors and professor in the Department of Environmental Health Sciences, helped to establish an expert consultant team from UAlbany (Lin and Bloom, who is now at George Mason) and Sun Yet-Sen University (Zeng and Dong) to guide study design, questionnaire development for IVF couples, and biological sampling collection for colleagues from the People's Hospital of Guangxi Zhuang Autonomous Region.

“It’s usually quite invasive to collect follicular fluid, but it is done routinely as a part of IVF, giving us a unique opportunity to examine the potential impact of PFAA in follicular fluid on female fertility,” explains Lin. “This may be one of the largest studies in this field, and the few epidemiological studies that looks at this relationship—and it’s important to look at so that we can better understand how environmental contaminants may impact the success of IVF.”

729 women who enrolled in the Guangxi IVF and the Environment Study in Guangxi province, China, and were going into their first IVF cycle volunteered to participate in this study. PFAA concentrations in their follicular fluid were analyzed, along with the health of their eggs. The study also looked at the structural makeup of the PFAA—either linear or branched— to see if this had an impact.

“Linear and branched PFAA is based on the isomer structures—the relative position of perfluoromethyl substitution,” explains Xiaowen Zeng, lead author. “If there is one or more perfluoromethyl branched chains on the PFAA structure, then it is called a branched PFAA isomer. Branched PFAA isomers in the environment are from manufacturing and environmental biotransformation.”

Over 85 percent of follicular fluid samples in the study contained eight different PFAA types (n-PFOS, n-PFOA, PFDA, PFHxS, PFHpS, PFNA, PFUnDa, and PFTrDA). Higher amounts of PFAA in follicular fluid was associated with a lower high-quality embryo rate and a lower maturity rate for the egg cells, which is a mediator in the pathway of PFOS/PFOA exposure and adverse IVF outcomes. This study also found that branched PFOS isomers may have a stronger effect than linear PFOS isomers.

“These findings provide policy makers and regulators additional evidence to manage the use of PFAA,” says Lin. “And while it’s important to understand the impact of PFAA on IVF outcomes, ideally a future step would look at the associations between follicular fluid PFAA with pregnancy and birth outcomes to better understand the impact that PFAA is having on health at birth.”

The full report can be found in Environmental Health Perspectives.