Wildfire smoke may be impacting fertility treatments, with a recent study indicating a dramatic drop in IVF pregnancy success rates during periods of unhealthy air quality. The research, conducted in New York City during the summer of 2023 when smoke from Canadian wildfires caused severe air pollution, analyzed 190 embryo transfers.
Researchers examined the Air Quality Index (AQI) on the day of each embryo transfer and compared pregnancy outcomes, while also accounting for factors such as maternal age and embryo quality. On days with good air quality, the success rate for embryo transfers was approximately 62%. Moderate air quality showed a slightly higher, though not statistically significant, rate of 65%.
However, on days when the AQI reached unhealthy levels, the pregnancy rate plummeted to 27%. This suggests that even smoke from distant wildfires can have a negative effect on fertility treatments.
"My hypothesis is that it doesn’t have to do with the actual lab itself or the transfer itself, but more in the days leading up to it and the days after it," stated Dr. Randi Goldman, an author of the study and attending physician at Northwell Fertility. "The person who had that embryo transfer is then exposed to these potential environmental issues, and then it might be kind of that larger issue that’s contributing to the success rates."
The study authors believe that microscopic pollution particles, known as PM2.5, present in wildfire smoke could be the cause. These particles can penetrate deep into the lungs and enter the bloodstream, potentially triggering inflammation and oxidative stress. The researchers posited that short-term exposure to these particles might interfere with embryo implantation.
"It’s important for anybody undergoing fertility treatment, [or any] reproductive health treatment, to think about this as something that’s important," Goldman said.
While rescheduling embryo transfers is not always feasible, the study suggests that air quality could be a factor for doctors and patients to consider. The authors proposed that on days with poor air quality, patients might consider cryopreservation of embryos and deferring the transfer to a later date when air quality improves.
Goldman also advised patients to minimize other environmental exposures before and after embryo transfers, emphasizing that tobacco smoke has a far greater negative impact. During periods of unhealthy air quality, she recommended staying indoors. For those who must go outside, a properly fitted KN95 mask could help reduce exposure, and using a high-quality HEPA air filter indoors was also suggested.
The study, which involved one fertility clinic and a limited number of embryo transfers, highlighted the need for further research into the effects of air pollution on fertility. "There needs to be more research on this topic. It’s not something that you hang your hat on. You never do that with a single study," Goldman noted. "But I think it really starts the conversation for a potential modifiable factor that we have in the reproductive health world."
The findings emerged as several parts of the United States experienced significant air quality degradation due to smoke from wildfires in Canada. New York City, for instance, saw its air quality dip to "very unhealthy" levels, prompting public health advisories to stay indoors and limit outdoor activities.