Obstetrician Leonie replies: There's been lots of research into the safety of taking asthma medications during pregnancy. In general all the drugs are safe, but it is always a good idea to book an appointment to see a doctor as early as possible so that your asthma treatment can be reviewed.
The most important thing you can do now is keep your asthma under control - do what you can to avoid severe attacks, which will reduce your oxygen levels and potentially your baby's, too. Asthma usually stabilises or improves slightly in pregnancy. In the rare cases where it does worsen, it's most likely because the woman hasn't taken her medication properly. Asthma attacks during labour are rare, so as long as you manage your condition you won't require any special monitoring.