Safety concerns may lead to poor adherence and discontinuation of asthma medications during pregnancy. (Photo: Pixabay)

Women with asthma who use short-acting inhalers to control symptoms may take longer to conceive than women without asthma, a recent study suggests.

Researchers examined data on 5,617 women during their first pregnancies, including 1,106 who said they had been diagnosed with asthma. The women had babies between 2004 and 2011 in New Zealand, Australia, Ireland and the UK.

Compared with non-asthmatics, women with current asthma who used only short-acting “rescue” medications like albuterol were 15 percent less likely to have conceived in any given monthly cycle, the study found. Women on rescue medications were also 30 percent more likely to have taken more than 12 months to conceive.

“While we found that asthma was linked with reduced fertility, the most striking finding was that this relationship was only observed among the group of women relying on short-acting asthma relievers alone to manage their asthma,” said lead study author Dr. Luke Grzeskowiak of the University of Adelaide.

“No relationship between the use of long-acting preventer asthma medications and fertility was seen,” Grzeskowiak said by email. “This provides reassuring evidence that women using long-acting asthma medications, to prevent asthma symptoms and maintain good asthma control, should continue to take these when trying to conceive.”

Long-acting asthma medications such as inhaled corticosteroids work by reducing inflammation in the lungs. Inflammation is a key step in triggering narrowing of the airways, which makes it more difficult for those with asthma to breathe.

While short-acting asthma medications can help relax the airway to treat asthma symptoms, such as wheezing, they are not able to reduce the underlying inflammation and therefore cannot prevent future symptoms.

Several studies have linked asthma to reproduction-related problems in women, but results have been mixed and the connection is poorly understood.

The study wasn’t a controlled experiment designed to prove whether or how asthma or short-acting asthma drugs might directly cause infertility. It’s possible that some women might struggle to conceive if their asthma was poorly controlled with short-acting medications.

Another limitation is that researchers relied on women to accurately recall and report on any current or prior asthma diagnosis. Researchers also lacked data on asthma control and lung function during pregnancy.

But it’s possible that inflammation may play a role in making it harder to conceive, and the findings suggest that women with asthma should take steps to manage symptoms before trying to conceive, researchers note in the European Respiratory Journal.

“It has been hypothesized that asthma reduces uterine blood supply and increases infiltration of inflammatory cells into the (uterine lining), which impairs implantation and fertility,” said Dr. Eyal Sheiner of Soroka University Medical Center and Ben-Gurion University of the Negev in Beer-Sheva, Israel.

“Preventer medications may play a protective role in improving asthma control and reducing associated systemic inflammation which may drive impaired fertility,” Sheiner, who wasn’t involved in the study, said by email.

Poorly controlled asthma during pregnancy can increase the risk that women will develop a severe form of high blood pressure known as preeclampsia, and it can also lead to restricted fetal growth and preterm deliveries as well as underweight infants.

Like many medications, long-acting preventive asthma drugs and inhaled corticosteroids haven’t been tested in pregnant women or proven safe for use during pregnancy. Doctors often advise women with asthma to get regular lung function tests during pregnancy, and to take medications if they have severe symptoms.

“Safety concerns may lead to poor adherence and discontinuation of asthma medications during pregnancy, with negative impacts on asthma control and pregnancy outcomes,” Sheiner said. “It is important to know that these medications improve pregnancy outcomes, and also fertility.”