Taking painkillers during pregnancy does not cause childhood asthma, study finds

In a large Swedish study, researchers investigated the link between mothers taking painkillers during pregnancy and the development of childhood asthma.

Several previous studies have shown a link between mothers taking paracetamol during pregnancy and an increased risk of children developing wheezing or asthma. However, it is not known whether other painkillers show a similar association. It is also not clear whether this is a “cause-and-effect” link or a marker for another causal factor.

Researchers explored these questions in a large study in Swedish mothers and children. They recently reported their findings in the European Respiratory Journal.

Studies have shown a link between taking paracetamol during pregnancy and childhood asthma

The researchers used Swedish health register data from over 490,000 mothers and their children. They examined mothers’ prescriptions for painkillers during pregnancy and the risk of childhood wheeze or asthma in their children. They also collected data from fathers and siblings to adjust for factors which might affect the results.

Children of women who had been prescribed paracetamol during pregnancy had a 50% increased risk of asthma at 5 years of age. A similar increased risk was seen in children of women who had been prescribed codeine (42%), or migraine medication (48%). These painkillers work in different ways but are associated with a similar increased risk of childhood asthma.

“Our interpretation of this is that it’s less likely that the drugs are responsible for the asthma. Instead, it seems more likely that another factor that we haven’t measured is linked to use of these drugs and to asthma risk,” commented Professor Seif Shaheen, Professor of Respiratory Epidemiology at Barts and The London School of Medicine & Dentistry, London, UK, the lead author of the study, in a press release.

Professor Shaheen and his team suggest that pregnant women who need prescription painkillers are likely to be suffering from chronic pain. The stress that chronic pain causes can have profound effects on the body, including hormonal effects, and there is evidence of a link between mothers’ stress levels during pregnancy and risk of childhood asthma.

The link between painkillers during pregnancy and childhood asthma not “cause and effect”

The researchers concluded that it is important to manage chronic pain during pregnancy and that painkillers should be prescribed as needed. Women should also feel reassured that the occasional use of over-the-counter paracetamol during pregnancy is unlikely to cause asthma in their children.

Commenting on the research, Professor Tobias Welte, President of the European Respiratory Society, who was not involved in the study, noted “Previous research suggested these two (paracetamol and childhood asthma) were linked in some way, but this large study suggests that this may not be a simple cause and effect relationship,” He added that further research was needed to study the complex reasons why so many children develop asthma. 

Written by Julie McShane, Medical Writer

 References

1. Shaheen SO, Lundholm C, Brew BK, et al. Prescribed analgesics in pregnancy and risk of childhood asthma. European Respiratory Journal 2019; DOI:10.1183/13993003.01090-2018.
2. European Lung Foundation. Press release, 17 March 2019 https://www.eurekalert.org/pub_releases/2019-03/elf-ssp031419.php