Acute asthma during pregnancy.

Background: Acute asthma during pregnancy is potentially dangerous to the fetus. The aim of this study was to investigate the effect of an acute attack of asthma during pregnancy on the course of pregnancy or delivery, or the health of the newborn infant, and to identify undertreatment as a possible cause of the exacerbations.
Methods: Five hundred and four pregnant asthmatic subjects were prospectively followed and treated. The data on 47 patients with an attack of asthma during pregnancy were compared with those of 457 asthmatics with no recorded acute exacerbation and with 237 healthy parturients.
Results: Of 504 asthmatics, 177 patients were not initially treated with inhaled corticosteroids. Of these, 17% had an acute attack compared with only 4% of the 257 patients who had been on inhaled anti-inflammatory treatment from the start of pregnancy. There were no differences between the groups as to length of gestation, length of the third stage of labour, or amount of haemorrhage after delivery. No differences were observed between pregnancies with and without an exacerbation with regard to relative birth weight, incidence of malformations, hypoglycaemia, or need for phototherapy for jaundice during the neonatal period.
Conclusions: Patients with inadequate inhaled anti-inflammatory treatment during pregnancy run a higher risk of suffering an acute attack of asthma than those treated with an anti-inflammatory agent. However, if the acute attack of asthma is relatively mild and promptly treated, it does not have a serious effect on the pregnancy, delivery, or the health of the newborn infant.