Taking paracetamol during pregnancy could increase the risk of autism in boys and attention-related and hyperactivity symptoms in girls and boys, the first study of its kind has revealed.
Writing in the latest edition of the International Journal of Epidemiology, Spanish researchers warn that paracetamol could be harmful to neurodevelopment after they recorded a 30% increased risk of developing some attention functions, and an increase of two clinical symptoms of autism spectrum symptoms in boys.
Their study involved 2,644 pregnant mothers and it continued until the youngsters were five years old.
They were asked about their use of paracetamol during pregnancy and how often they took it – never, sporadic, or persistent – and then 88% were evaluated when their child was one-year-old and 79.9% were evaluated when their offspring was five years old.
The research team found that 43% of children evaluated at age one and 41% assessed at age five were exposed to paracetamol at some point during the first 32 weeks of pregnancy.
However, when children were assessed at five years, the researchers found that children who had been exposed were at higher risk of hyperactivity or impulsivity symptoms, while youngsters of mothers who had taken paracetamol “persistently” had poorer performance on a computerised test measuring inattention, impulsivity and visual speed processing.
Boys who had been persistently exposed to paracetamol while in the womb had more autism spectrum symptoms.
Lead author Claudia Avella-Garcia, researcher at CREAL, an ISGlobal allied centre in Barcelona, said: “Although we measured symptoms and not diagnoses, an increase in the number of symptoms that a child has, can affect him or her, even if they are not severe enough to warrant a clinical diagnosis of a neurodevelopmental disorder.”
Co-author Dr Jordi Júlvez, also a researcher at CREAL, said one reason paracetamol could be harmful to neurodevelopment is because it relieves pain by acting on cannabinoid receptors in the brain.
“Since these receptors normally help determine how neurons mature and connect with one another, paracetamol could alter these important processes,” he said.
“It can also affect the development of the immune system, or be directly toxic to some foetuses that may not have the same capacity as an adult to metabolise this drug, or by creating oxidative stress.”
Avella-Garcia also said it was possible that boys are more likely to have autism spectrum symptoms because the male brain may be more vulnerable to harmful influences during early life.
“Our differing gender results suggest that androgenic endocrine disruption, to which male brains could be more sensitive, may explain the association,” she added.
The Royal College of Midwives said more work was needed on the association between paracetamol and autism and hyperactivity symptoms.
Louise Silverton, director for midwifery at the RCM, added: “This is an important study and whilst most women should if possible avoid taking medications during pregnancy, paracetamol has previously been seen as a low risk drug to take if necessary and needed.
“Paracetamol should be used during pregnancy on medical or midwifery advice where women absolutely require something to, for example, help reduce fever.
“That said, it’s important to remember most women who use paracetamol minimally and only when necessary during their pregnancy will deliver a healthy baby.”
Avella-Garcia C, Julvez J, Fortuny J et al. Acetaminophen Use in Pregnancy and Neurodevelopment: Attention Function and Autism Spectrum Symptoms. International Journal of Epidemiology July 2016; doi: 10.1093/ije/dyv
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