New research has shown that exposure to fine particulate matter before IVF egg retrieval can reduce the odds of achieving a live birth by almost 40%.
The findings, presented today at the ESHRE 40th Annual Meeting in Amsterdam, have revealed that exposure to fine particulate matter (PM) before the retrieval of oocytes (eggs) during IVF can reduce the odds of achieving a live birth by almost 40%.
IVF is one technique to help people with fertility problems have a baby. During IVF, an egg is removed from the woman’s ovaries and fertilised with sperm in a laboratory. The fertilised egg, called an embryo, is returned to the woman’s womb to grow and develop.
Discovering the role of air pollution in IVF success rates
The researchers analysed 3,659 frozen embryo transfers from 1,836 patients over eight years. The median age for a female was 34.5 years at the time of egg retrieval and 36.1 years at the time of frozen embryo transfer. The study examined air pollutant concentrations over four exposure periods before egg retrieval (24 hours, 2 weeks, four weeks, and three months), with models created to account for co-exposures.
Researchers analysed PM10 exposure in the two weeks leading up to egg collection. They found that the likelihood of a live birth decreased by 38% (OR 0.62, 95% CI 0.43-0.89, p=0.010) when comparing the highest quartile of exposure (18.63 to 35.42 µg/m3) to the lowest quartile (7.08 to 12.92 µg/m3).
Furthermore, increasing PM2.5 exposure in the three months before egg retrieval was also associated with decreased odds of IVF live birth, falling from 0.90 (95% CI 0.70-1.15) in the second quartile to 0.66 (95% CI 0.47-0.92) in the fourth quartile.
Importantly, the negative impact of air pollution was observed despite excellent overall air quality during the study period, with PM10 and PM2.5 levels exceeding WHO guidelines on just 0.4% and 4.5% of the study days, respectively.
Dr Sebastian Leathersich, lead author of the study, explained, “This is the first study that has used frozen embryo transfer cycles to separately analyse the effects of pollutant exposure during the development of eggs and around the time of embryo transfer and early pregnancy. We could therefore evaluate whether pollution was having an effect on the eggs themselves, or on the early stages of pregnancy.”
“Our results reveal a negative linear association between particulate matter exposure during the 2 weeks and 3 months prior to oocyte collection and subsequent live birth rates from those oocytes. This association is independent of the air quality at the time of frozen embryo transfer. These findings suggest that pollution negatively affects the quality of the eggs, not just the early stages of pregnancy, which is a distinction that has not been previously reported.”
Air pollution: A concerning environmental risk to health
Outdoor air pollution is one of the greatest environmental risks to health and is estimated to cause over four million premature deaths per year worldwide. Exposure to fine particulate matter can cause various health conditions, including cardiovascular and respiratory diseases.
Dr Leathersich furthered, “Climate change and pollution remain the greatest threats to human health, and human reproduction is not immune to this. Even in a part of the world with exceptional air quality, where very few days exceed the internationally accepted upper limits for pollution, there is a strong negative correlation between the amount of air pollution and the live birth rate in frozen embryo transfer cycles. Minimising pollutant exposure must be a key public health priority.”
Professor Dr Anis Feki, Chair-Elect of ESHRE, commented, “This important study highlights a significant link between air pollution and lower IVF success rates, with a notable reduction in live births associated with higher particulate matter exposure before oocyte retrieval. These findings emphasise the need for ongoing attention to environmental factors in reproductive health.”
