Wildfire smoke may affect IVF

Poor air quality caused by wildfires may affect treatment outcomes in patients undergoing IVF.

The impact of environmental factors on reproductive outcomes is well established, with many studies linking air pollution to infertility and impacted reproductive development (see BioNews 1218, 1191 and 1133). A retrospective cohort study conducted by researchers at Oregon Health & Science University (OHSU) has now linked wildfire smoke exposure to reduced success in some aspects of fertility treatment.

'The unfortunate reality is that we are seeing more wildfires because of climate change, so I worry about how this will continue to affect not only patients undergoing fertility treatments, but all individuals who are trying to conceive,' said lead author Dr Molly Kornfield from the OHSU Centre for Women's Health in Portland, Oregon.

The study, published in the journal Fertility and Sterility, assessed the impact of unhealthy air quality exposure following the 2020 Oregon wildfires, by looking at records from 69 patients who underwent ovarian stimulation and IVF treatment in the six weeks preceding the wildfires, which resulted in a ten-day exposure period of unhealthy air quality.

During an IVF cycle, following egg collection and fertilisation, embryos are allowed to develop to the blastocyst stage, and can either be frozen for future use or immediately transferred to a patient's uterus. Patients exposed to air pollution during the developmental phase of their treatment cycle were found to yield fewer blastocysts compared to patients who were not.

'Part of what makes your IVF cycle successful is often not just having one blastocyst or one embryo for transfer, but having a few,' said Dr Kornfield. 'For particular patients, in particular situations, we may consider delaying or cancelling if things can be predicted, and then advising patients to take as much precaution as possible.'

Despite observing lower blastocyst yield among exposed patients, researchers did not note any difference in pregnancy outcome between patients who were exposed to wildfire smoke and those who were not. Previously conducted studies have however linked air pollution to lower live birth rates in patients undergoing frozen embryo transfer (see BioNews 1247).

OHSU researchers are planning more studies to investigate the impact of air pollution on other reproductive outcomes, including sperm quality, miscarriage rates, and effects on naturally-conceived pregnancies.

'Of course, we need to take broader measures to slow climate change and reduce the impact and extent of these fires,' Dr Kornfield said. 'Our hope is that this research informs preparedness measures that can ensure the best possible outcomes for our patients when we do face these serious air quality crises.'