A new study from the European Respiratory Journal has shown that woman with asthma take longer to get pregnant than woman without asthma. A group of 15,000 women were surveyed. When asked if they spent over a year trying to get pregnant, 21% of women without asthma said yes whereas 27% of woman with asthma said yes. If their asthma went untreated, the percentage was even higher.

The good news is, overall both groups of women had the same number of children. So asthma doesn’t seem to stop women from having kids, but it may make conception more difficult. Also, by treating asthma and regularly taking asthma medication woman can reduce the amount of time it takes to get pregnant.

More research is needed to show why asthma affects pregnancy, but there are two major theories. One is that because asthmatic women tend to get sick more frequently, they have sex less frequently. As researcher Dr. Avner Hershlag put it, “When someone is sick and asthmatic, their focus changes from ‘I’m going to get pregnant,’ to ‘I’m going to get better.’”

The other theory is that the inflammation caused by asthma affects not only the respiratory system but the uterus as well. If the inflammation altered the blood supply to the uterus it may make it more difficult for eggs to implant there. This theory would also explain the results of an older study which found asthmatic women had an increased risk of miscarriage.

So if you have asthma and are trying to get pregnant, just remember to take your medicine regularly and avoid your asthma triggers and you should be fine.