Here is a little about the main medicines used in asthma.
o Steroid Inhalers based on Becotide (beclomethasone dipropionate, now a common drug under all sorts of other names too) and Pulmicort (budesonide).
These steroids have been used for decades and on a massive scale, including a vast amount of use by women who were pregnant. There have been no evidence of harmful effects. In fact, in small doses these steroids are thought to offer additional protection to the baby from lack of oxygen.
o Cromoglycate (Intal, Lomudal, Cromolyn etc.) and Nedocromil (Tilade, Tilarin, etc.)
These asthma preventers are not steroids, but their safety record is very good indeed. No harmful effects on unborn babies have been recorded even though they have been in widespread use since 1968. They are still excellent medicines for people in whom they prove sufficient.
o Theophylline (many trade names)
Unlike inhaled drugs, theophylline is taken by mouth, usually as tablets, and, unlike the inhaled steroids, it is not broken down slowly by the liver. Despite widespread use, no harmful effects on unborn children have been described.
o Salbutamol (Ventolin, many other brand names)
Salbutamol has been in widespread use since the 1960s. When given in large doses by infusion or injection near the time when the baby is to be born, it can delay birth, and in fact it has been used for this purpose. In doses which are more usually inhaled for asthma it is harmless throughout pregnancy.
o Terbutaline (Bricanyl) is very similar to salbutamol. All the conclusions for salbutamol should apply.
These work in the same way as the ordinary relievers such as salbutamol and terbutaline, with the difference that they stick to the cells in the body on which they act, and so work for much longer. The side-effects are the same, namely tremor, increased pulse rate, and palpitations (being able to feel your heart beating). They have been introduced much more recently, but no hazards in pregnancy are known.
o Salmeterol xinafoate (Serevent) No hazards during pregnancy are known.
o Eformoterol (Foradil)
No hazards during pregnancy are known.
Steroid Tablets or Injections
You should only need these for emergencies, such as sudden bad asthma attacks, or if your asthma is so bad all the time that you are one of the few people who do need them regularly. If so, you need them, and your baby would be much worse off if you did not take them. Such strong steroids do affect the unborn child, but the current knowledge of these effects seems to be that they are remarkably mild.
Always discuss the use of any treatment or medicine with your doctor, whether you are pregnant or not.