Others said that it was possible that something besides the antibiotics was responsible, such as the illness the drugs were prescribed for.
This study, it doesn't tell us whether it's the antibiotic use or whether it's the infection. That's one thing we can't decipher, said Anita Kozryskyj, a professor at the University of Alberta who also studies the antibiotics-asthma link but wasn't involved in the new study.
The results don't suggest that women should avoid antibiotics since some infections can be quite dangerous to a fetus, she said, adding that Bisgaard's study suggests that the development of asthma might start before birth, something researchers hadn't studied very closely.
We're beginning to appreciate that some of the origins of asthma and changes to the immune system, maybe they start earlier than right after birth, she added.