Effectiveness of IVF compromised by poor air quality

The 40th annual meeting of the European Society of Human Reproduction and Embryology has been presented with research that suggests exposure to particulate matter, prior to oocyte retrieval (the removal of developing eggs from the ovaries) during IVF, can reduce the odds of a live birth by nearly 40%.

The study looked at PM10 exposure in the two weeks leading up to the procedure, finding that the odds of a live birth decreased by 38% when comparing the highest quartile of air pollution exposure (18.63 to 35.42 µg/m³) to the lowest (7.08 to 12.92 µg/m³).

The research, which took place over eight years in Perth, Australia, analysed 3,659 frozen embryo transfers from 1,836 patients along with air quality over four exposure periods prior to the eggs’ removal: 24 hours, two weeks, four weeks, and three months.

An increase in PM2.5 exposure in the three months prior to oocyte retrieval was also associated with decreased odds of live birth.

Of some concern is the fact that air quality during the trial period was generally very good, 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, explains, ‘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.

‘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, said: ‘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.’

This research adds to a body of work that has made similar associations in the past.

Recent research in the US found that laboratory exposure to unhealthy air led to a significant reduction in cycles with no blastocysts (a blastocyst forms about five to six days after a sperm fertilizes an egg). Amongst the exposed group this occurred three times across 15 subjects, whereas it only happened once among the 44 unexposed members of the cohort.

To make matters worse the same research group, from Oregon Health & Sciences University, also found that poor air quality from wildfire smoke lead to a decrease in total motile sperm count.

30 men provided two semen samples each, one before exposure to wildfire smoke and one after. It was found that there was a considerable drop in total motile sperm after the fires for 20 of them.

This has led to questions about whether IVF treatment should be suspended during periods of poor air quality such as those brought about by wildfires in North America.