Exposure to fine particulate matter (PM) before egg retrieval in IVF (in vitro fertilization) may reduce the chance of a live birth by around 40%, according to a new study presented at the 40th Annual Meeting of ESHRE in Amsterdam.

The research focused on PM10 exposure in the two weeks prior to egg collection. It found that high exposure levels (18.63 to 35.42 µg/m3) reduced the chance of live birth by 38% compared to low exposure levels (7.08 to 12.92 µg/m3).

The study, conducted over eight years in Perth, Australia, and to be published in Human Reproduction, analyzed 3,659 frozen embryo transfers from 1,836 patients.

The average age of the women was 34.5 years at the time of egg retrieval and 36.1 years at the time of embryo transfer. Air pollutant levels were examined in four periods before egg retrieval: 24 hours, 2 weeks, 4 weeks, and 3 months.

The study also found that higher exposure to PM2.5 in the three months before egg harvesting was associated with a reduced live birth rate, with the probability decreasing from 0.90 in the second quartile to 0.66 in the fourth quartile.

Despite generally good air quality during the study period, the negative impact of pollution was evident. PM10 and PM2.5 levels exceeded WHO guidelines on the study days at just 0.4% and 4.5%, respectively.

Lead author Dr. Sebastian Ledersich said: “This is the first study using a frozen embryo transfer cycle to separately analyse the effects of pollutant exposure during egg development and the early stages of pregnancy. Our findings suggest that pollution affects egg quality, not just the early stages of pregnancy.”

Outdoor air pollution is a major health risk, causing more than 4 million premature deaths each year.

“Climate change and pollution are major threats to human health, including reproduction. Even in areas with good air quality, there is a strong association between pollution and lower live birth rates in IVF cycles. Reducing pollution exposure should be a major public health priority,” said Dr. Ledersich.

Researchers said the study highlights a significant link between air pollution and lower IVF success rates.