A scientific team has discovered that pregnancy can be negatively affected by short exposures to high levels of ozone. A combination of bright sunlight and heat with compounds from industrial emissions, gasoline vapours and car exhausts in the warmer months can increase ozone layers.
Ozone is an air-pollutant that can affect heart and lung health, and possibly affect women’s ability to successfully conceive.
Carla R. Caruso, M.D, a resident physician at the Pennsylvania State University College of Medicine said, “We found that breathing ozone on the day of ovulation not only decreased progesterone levels in female mice, but also reduced the number of ovulated eggs.”
The levels of progesterone in the blood of female mice on the day of ovulation decreased from a normal value of 8 nanograms per milliliter (ng/ml) in females breathing filtered air, to an average of 2 ng/ml in mice breathing ozone.
The investigators compared the number of ovulated eggs the following morning, discovering a statistically significant reduction of 30 percent in females exposed to ozone. Expression of key enzymes involved in the progesterone synthesis pathway was also significantly reduced in the ovaries of ozone-exposed female mice.
Leader of the research team, Patricia Silveyra, Ph.D., from the Pennsylvania State University College of Medicine said they’d inadvertently made the discovery while studying sex differences in mice affected by ozone on lung inflammation.
“Population studies evaluating fertility complications in geographical areas with high and low ozone pollution levels, as well as clinical studies conducted in women of reproductive age can help elucidate these concerns,” Silveyra said, noting that further research was necessary.
The researchers will now focus on understanding the impact on the ovulation of the mice when affected by elevated levels of ozone.