When wildfire smoke turned New York's skies an eerie orange last summer, it may have done more than ruin the skyline photos. A new peer‑reviewed study from a New York fertility center reports that embryo transfers performed on days with wildfire‑driven "Unhealthy" air were far less likely to result in a clinical pregnancy than transfers done when air quality was better. During the heavy smoke that settled over the region in June and July 2023, pregnancy rates dropped to the high 20s on the worst days, compared with the low 60s on days with good or moderate air. For patients and clinics trying to time an embryo transfer just right, that kind of swing is hard to ignore.
Study Details And Results
The retrospective cohort study looked at 190 embryo transfers performed between June 1 and July 31, 2023, at a single academic fertility center in New York, according to Human Fertility. The authors report clinical pregnancy rates of about 62.0% on Good Air Quality Index (AQI) days and 64.9% on Moderate days, compared with just 27.3% on Unhealthy days, and say those gaps were statistically significant. When they focused specifically on single euploid embryo transfers, the same pattern showed up in the data, although some subgroup comparisons were no longer statistically significant because the numbers were small.
How This Fits With Other Research
The New York findings line up with a broader body of work suggesting that short bursts of exposure to fine particulate matter (PM2.5) and other pollutants can drag down assisted‑reproduction outcomes. A meta‑analysis in BMC Public Health found that higher PM2.5 and other pollutant levels were tied to lower biochemical and clinical pregnancy rates, as well as fewer live births across multiple ART studies. Taken together, the pooled literature suggests the Human Fertility results are in step with existing epidemiologic signals, even as researchers caution that more work is needed to nail down the exact mechanisms and timing.
What Smoke Does In The Body
Wildfire smoke is loaded with PM2.5, particles small enough to reach the deepest airways of the lungs and, according to the World Health Organization, to enter the bloodstream and trigger inflammation and oxidative stress. The Human Fertility authors argue that this kind of inflammatory response is a plausible route by which smoky air on the day of embryo transfer could disrupt implantation and very early pregnancy. Public‑health research has also noted that wildfire‑derived particulates can have particularly high oxidative potential compared with some other PM2.5 sources, offering another possible clue to why these plumes might pack such a punch.
Clinics And Doctors Respond
Dr. Randi Goldman, an attending physician at Northwell Fertility and a co‑author on the study, told the New York Post that smoke carried miles from distant fires can plausibly interfere with implantation. Coverage of the paper notes that the authors recommend clinics consider embryo cryopreservation and postponing transfers on days when air quality is especially poor, an approach some centers may already be discussing with patients when the sky turns hazy.
What Patients Should Talk About With Their Clinic
For patients planning a transfer, the menu of options includes freezing embryos for transfer at a later date, rescheduling when clinic logistics allow, or weighing the risks and benefits directly with their care team. New York officials have urged residents to limit outdoor activity when AQI readings are poor, and Mayor Zohran Mamdani has advised New Yorkers to stay indoors during severe air events, according to local coverage in 1010 WINS. Inside the home, using certified HEPA air purifiers and cutting down on time outdoors during smoky spells can reduce exposure to PM2.5, and an analysis in Nature Health finds that indoor air filtration is a cost‑effective way to blunt wildfire smoke during peak season.
