Air pollution is the enemy of aspiring parents. Exposure to fine particulate matter (PM), before the collection of oocytes during in vitro fertilization, can reduce the chances of achieving the birth of a child by almost 40%. This was revealed by a pioneering study, presented at the 40th annual congress of Eshre, the European Society of Human Reproduction and Embryology, underway in Amsterdam, and published in ‘Human Reproduction’.
In recent years, the link between pollution and reproductive health has become increasingly clear. New evidence now comes from this Australian study, which analyzed exposure to PM10 in the two weeks prior to egg collection, finding that the chances of a live birth decreased by 38% when comparing the highest exposure quartile (from 18.63 to 35.42 µg/m3) to the lowest (from 7.08 to 12.92 µg/m3). In practice, the more fine particulate matter you breathe, the lower your chances of a baby arriving.
To obtain these results, the researchers examined 3,659 frozen embryo transfers from 1,836 patients over eight years in Perth. The average age of the women was 34.5 years at the time of egg retrieval and 36.1 years at the time of implantation. Concentrations of air pollutants were assessed over four exposure periods before egg retrieval (24 hours, 2 weeks, 4 weeks and 3 months), with models created to account for co-exposures. Increased exposure to PM2.5 in the 3 months before egg retrieval was also associated with a decreased likelihood of live births. And that’s not all. The researchers highlight that “the negative impact of pollution was observed despite the excellent overall air quality during the period considered, with levels of PM10 and PM2.5 exceeding the WHO threshold values on only 0.4% and 4.5% of the study days”.
“This is the first study to use frozen embryo transfer cycles to separately analyse the effects of exposure to pollutants during oocyte development, the period of embryo implantation and early pregnancy,” said lead author Sebastian Leathersich, a fertility specialist and gynaecologist at King Edward Memorial Hospital in Subiaco. “Our results reveal a negative linear association between exposure to particulate matter during the 2 weeks to 3 months before oocyte collection and subsequent live birth rates from those oocytes. They therefore suggest that pollution negatively affects oocyte quality and not just early pregnancy, an effect that has not been reported previously.”
While the correlation between pollution and poorer reproductive outcomes is now clear, the underlying mechanisms are still unclear. “Climate change and pollution remain the greatest threats to human health, and reproduction is not immune,” Leathersich continues. “Even in a part of the world with exceptional air quality, where very few days exceed internationally accepted maximum pollution limits, there is a strong negative correlation between fine particulate matter levels and birth rates in frozen embryo transfer cycles. Minimizing exposure to pollutants must be a key public health priority.”
This is also a priority for Eshre President-elect Anis Feki. “This important study highlights a significant link between air pollution and lower IVF success rates,” he said, “with a significant reduction in live births associated with increased exposure to particulate matter prior to egg retrieval. These findings underscore the need for continued attention to environmental factors in reproductive health.”
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