Women who want to get pregnant should wear masks when going outdoors and turn on air purifiers in their homes during periods of severe air pollution, as pollution could lead to premature ovarian failure, a doctor said on Monday.

They should also maintain healthy dietary and living habits, Tainan Daan Hospital for Women and Children physician Lin Pei-hsuan (林佩萱) said.

Only 1 to 3 percent of women experience the condition, in which women under 40 have ovaries whose function resembles that of women over 50, Lin said.

The condition has become more widespread in Taiwan over the past decade, while the average age of women diagnosed with it has been declining, Lin said, adding that she has treated many “newlywed women” with the condition.

Lin cited a study published last year by University of Modena and Reggio Emilia professor Antonio La Marca, in which anti-Muellerian hormone (AMH) measurements were taken from 1,318 women living in Modena, Italy, from 2007 to 2017.

AMH is produced by the ovaries and is important in the development of the follicles that contain the eggs.

The study showed that AMH serum levels after the age of 25 were “inversely and significantly related to the women’s age, and also significantly related to environmental pollutants defined as PM10, PM2.5 and nitrogen dioxide,” Lin said.

PM2.5 refers to particulate matter smaller than 2.5 micrometers in diameter.

The research concluded that “environmental chemicals, as well as natural and artificial components of everyday diet, have the potential” to disturb or interfere with the biosynthesis, signaling or metabolism of the physiological role of hormones, Lin said.

The research is titled “Ovarian Reserve and Exposure to Environmental Pollutants Study,” she said.

Previous studies have documented the effects of air pollution on the quality of sperm, Lin said, adding that other studies corroborating La Marca’s findings would be worth following.

Other factors, such as a sedentary lifestyle, keeping irregular hours, excessive alcohol intake, smoking, excessive weight loss and mental stress, are considered to be directly related to premature ovarian failure, Lin said.

Young women with the condition or those older than 35 might consider having their eggs frozen to increase their chances of getting pregnant, she added.