Women with asthma who only use short-acting asthma relievers take longer to become pregnant than other women, but women with asthma who use long-acting asthma preventers conceive as quickly as other women, according to research published in the European Respiratory Journal.
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 per cent 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% longer to conceive on average. They were also 30% 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 research 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.