A Danish study of more than 64,000 mothers and children found an association between acetaminophen use during pregnancy and a higher likelihood of ADHD-related diagnoses, medication use and behaviors in children. Acetaminophen, also known as paracetamol and sold under brands including Tylenol, is commonly recommended for mild pain and fever during pregnancy.

Researchers analyzed data from the Danish National Birth Cohort, including mothers’ reports of medication use and their children’s behavior, as well as records of ADHD medication prescriptions and diagnoses of hyperkinetic disorder, a severe form of ADHD. More than half of the mothers reported taking acetaminophen during pregnancy. Those who reported any use had a 29% higher risk of having a child diagnosed with ADHD and a 37% higher risk of a hyperkinetic diagnosis. Use for 20 weeks or more was associated with a 50% higher risk of the child receiving ADHD medication. The study tracked the number of weeks of use but did not establish risks by dose.

The researchers and other experts stressed that the findings **do not prove acetaminophen causes ADHD**. ADHD-like behaviors are also not the same as an ADHD diagnosis. Other factors could help explain the association, including infections or pain experienced during pregnancy and genetic factors, since ADHD often runs in families. Researchers proposed that acetaminophen might affect hormones important to fetal brain development, but that explanation remains unproven.

Study author Dr. Beate Ritz said pregnant women should not worry about occasional use, but suggested avoiding frequent or long-term use until more is known. Experts emphasized weighing the benefits of treatment against potential risks; untreated illness can also pose risks during pregnancy. Dr. Jeffrey Chapa suggested considering non-drug approaches to pain, such as massage, baths or acupuncture. Tylenol maker McNeil Consumer Healthcare said pregnant and breastfeeding women should consult their doctors before taking medication and noted that no prospective randomized controlled studies have established a causal link to adverse child development.