It seems Asthma is linked to infertility, but not among women taking regular asthma preventers.

A European Lung Foundation-study said that women with asthma, who use long-acting asthma preventers, conceive as quickly as other women, breaking the previous conception that women with asthma who only use short-acting asthma relievers take longer to become pregnant than other women. The study was conducted on more than 5,000 women in Australia, New Zealand, the United Kingdom and Ireland and was led by Dr Luke Grzeskowiak.

He claimed that the results provide reassurance for asthmatic women that using inhaled corticosteroids to prevent symptoms does not appear to reduce fertility. Dr Luke explained, "Five to ten percent of all women around the world have asthma and it is one of the most common chronic medical conditions in women of reproductive age. Several studies have identified a link between asthma and female infertility, but the impact of asthma treatments on fertility has been unclear”.

"Studying the effect of asthma treatments in women who are pregnant or trying to get pregnant is important as women often express concerns about exposing their unborn babies to potentially harmful effects of medications”, he further noted. The researchers examined data from the international Screening for Pregnancy Endpoints (SCOPE) study, which recruited over 5,000 women expecting their first babies in the early stages of pregnancy. Women were asked if they had been diagnosed with asthma and, if so, which medicines they had used. They were also asked how long it had taken them to become pregnant.

More than ten percent of women in the study said they had asthma and, overall, these women took longer to get pregnant. When researchers separated this group according to the types of asthma treatments they were using, they found no difference in fertility between women using long-acting asthma treatments and women without asthma. But women using short-acting beta-agonists only took 20 percent longer to conceive on average. They were also 30 percent more likely to have taken more than a year to conceive, which the researchers defined as the threshold for suffering infertility.

This difference remained even after researchers took other factors which are known to influence fertility, such as age and weight, into account. The researchers acknowledge that they did not recruit women from the time that they started trying to conceive, meaning that the study excluded women who were unable to become pregnant naturally. They plan further studies involving women with asthma who are undergoing fertility treatments, to see whether improving asthma control could also improve fertility outcomes. The study is published in the European Respiratory Journal.