A new study from Swansea University suggests women who stop taking their asthma medication during pregnancy are at risk of giving birth prematurely and are less likely to breastfeed their babies.

Many women in the UK are prescribed medicines for asthma before or during pregnancy, at around 11.8% of the population. However, prescription records show that 28.3% of women had no prescriptions during pregnancy and this indicates that they discontinue their medication during pregnancy.

The study, published in PLOS ONE, found that women who stopped their asthma medication during pregnancy were at increased risk of preterm birth, whereas women who continued with their prescriptions were at lower risk.

Swansea University reports the data indicated that there was no increased risk of preterm birth for women prescribed only inhaled corticosteroids, which indicates well controlled asthma. The researchers also examined stillbirths and while the numbers were too low for full analysis, a similar trend was identified.

The research team used data from the Secure Anonymised Information Linkage (SAIL) Databank, a state of the art privacy protecting system housed in Swansea University, which is funded by the Welsh Government as part of the national research infrastructure.

Professor Sue Jordan, who led the study, said “To put this into context, we know from existing research that babies that are born before 32 weeks’ gestation have a 6.2% risk of cerebral palsy and a 40% risk of broncho-pulmonary dysplasia, and babies born before 37 weeks have a 1% risk of cerebral palsy and 40% risk of cognitive impairment.

“So it is likely that women who discontinue asthma medication in pregnancy, often without medical advice, are at greater risk of having preterm babies who would then be vulnerable to these associated medical conditions. This data, taken together with the data on lower breastfeeding rates, makes it clear that there are unmet needs amongst pregnant women with asthma.

“A good solution would be to programme primary care electronic records to alert health professionals to women who leave months between prescriptions for asthma medicines. These women could be offered closer monitoring, targeted support and active asthma management before, during and after pregnancy, which would more likely lead to much more positive outcomes.”