Collaborative ECHO research, led by Linda Kahn, PhD, MPH at NYU Langone Health, suggests traffic-related air pollution, secondhand smoke, and formaldehyde are associated with longer time to pregnancy. Specifically, exposure to particulate matter and nitrogen oxide gases lowered couples’ chances of becoming pregnant. Traffic and the burning of other types of materials besides gas and diesel, such as wildfires or other sources of combustion, create particulate matter and nitrogen oxide gases.
These results are based on a systematic review of 33 articles pertaining to air pollution and time to pregnancy, an indicator of a couple’s reproductive health. The team’s research, titled “Indoor and outdoor air pollution and couple fecundability: a systematic review,” is published in Human Reproduction Update.
Mounting evidence suggests an association between air pollution and longer time to pregnancy. The goal of this review was to compare results from previous studies and identify whether different types of pollution, such as pollution from traffic, chemicals in the workplace, and secondhand smoke, are consistently related to time to pregnancy.
To conduct this research, the team searched six science libraries and reviewed 33 relevant articles published in English between January 1, 1990 and February 11, 2021. Of these 33 articles, eight examined air quality, six looked at secondhand smoke exposure, and 19 studied air quality in the workplace. Researchers assigned each article a quality score based on the study design and extracted relevant data on time to pregnancy.
“This review shows that certain chemicals can increase the amount of time it takes for a couple to conceive, which may cause stress and lead them to seek fertility treatments,” said Dr. Kahn.
Researchers still need more insight into exactly how these chemicals affect reproduction. Future studies should be designed to collect more accurate exposure data, ideally from personal air monitors.
“Our team is still uncertain about whether the air people breathe around time of conception is most important or if there are certain life stages such as puberty when individuals may be especially susceptible to the harmful effects of air pollution,” Dr. Kahn added.
The ECHO Program will provide a useful framework for collecting more detailed information on how chemical exposures across the life course affect reproduction.