Taking paracetamol or other painkillers during pregnancy does not cause asthma in the offspring – but may indicate other factors increasing the risk, according to a large-scale study out today.
The link between painkillers and asthma is probably because the medicines have been taken for health problems that may contribute to the increased risk, researchers found.
Researchers analysed prescription data on painkillers of almost 500,000 women, supports earlier study findings that women taking paracetamol during pregnancy are more likely to have children who develop asthma- but concluded the painkillers are not the cause of the increased risk.
Instead, they think it could be related to the stress caused by severe pain, and the effects on the body, including on levels of some hormones, for the offspring’s increased risk of asthma.
Researchers say their results, published in the European Respiratory Journal, should reassure women if they need to take prescribed painkillers during pregnancy.
Lead researcher Professor Seif Shaheen, professor of respiratory epidemiology at Barts and The London School of Medicine and Dentistry, Queen Mary University of London, worked with Professor Catarina Almqvist and colleagues at the Karolinska Institute in Stockholm, Sweden, on the study.
They examined prescription data for 492,999 Swedish mothers and their children, comparing the types of painkillers taken during pregnancy and the rates of asthma diagnosis in the children. They also looked at other data on the mothers, fathers, and any siblings.
They found that children born to mothers who had been prescribed paracetamol during pregnancy had an increased risk of asthma. But women who had been prescribed opioids or migraine medication faced a similarly increased risk. The increase in risk for asthma at five years of age was 50% for paracetamol, 42% for codeine and 48% for migraine medication.
Professor Shaheen, who was the first scientist to discover a link between paracetamol use during pregnancy and an increase in the risk of asthma in children, said: “These different types of painkillers work in different ways – but our results suggest that, when women are prescribed them during pregnancy, the associated increases in children’s asthma rates are fairly similar for all types.
“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. For example, women who are taking prescribed painkillers are likely to be suffering from chronic pain.
“Severe pain, and the stress that it causes, have profound effects on the body, including on levels of some hormones, and there is evidence for a link between high levels of mothers’ stress in pregnancy and increased risk of asthma in the offspring.”
He said women should not avoid painkillers in pregnancy if they need them, adding that the latest study results suggest that it is not worthwhile to carry out a clinical trial into the effects of taking paracetamol during pregnancy.
Shaheen SO, Lundholm C, Brew BK, et al. Prescribed analgesics in pregnancy and risk of childhood asthma. Eur Respir J 18 March 2019
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