Relationship between short-acting asthma inhalers and fertility.
The researchers examined data on 5,617 women during their first pregnancies including 1,106 who had been diagnosed with asthma.
The women gave birth between 2004 and 2011.
Non asthmatic women who used rescue medication were 15% less likely to have conceived in a monthly cycle.
Women on rescue medication were also 30% more likely to have taken more than a year to conceive.
There was no relationship found between the use of long-acting preventer asthma medications and fertility.
Women on such medication to prevent asthma symptoms and maintain asthma control should continue to do so even when trying to get pregnant.