Acetaminophen use during pregnancy may increase the risk of behavioral problems during childhood, according to data published in JAMA Pediatrics.

Evie Stergiakouli, PhD, from the Medical Research Council Integrative Unit at the University of Bristol, United Kingdom, and colleagues assessed the relationship between childhood behavior problems and maternal prenatal acetaminophen use, postnatal acetaminophen use, and a partner’s acetaminophen use.

The investigators collected data from the Avon Longitudinal Study of Parents and Children (ALSPAC) between 1991 and 1992. They studied 7,796 mothers, along with their children and partners. To assess acetaminophen use, the participants completed a questionnaire at 18 and 32 weeks of pregnancy and when the child was 61 months old.

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“Children exposed to acetaminophen use prenatally are at increased risk of multiple behavioral difficulties. The associations were not observed for postnatal or partner’s acetaminophen use, which indicates that these behavioral difficulties might not be explained by unmeasured behavioral or social factors linked to acetaminophen use,” the study authors wrote.

 “Our findings suggest that the association between acetaminophen use during pregnancy and offspring behavioral problems in childhood may be due to an intrauterine mechanism.”

The results showed that 53% of women used acetaminophen at 18 weeks of pregnancy and 42% used acetaminophen at 32 weeks. Maternal prenatal acetaminophen use was associated with an increased risk of childhood conduct problems (risk ratio [RR]: 1.42) and hyperactivity symptoms (RR: 1.31). Acetaminophen use at 32 weeks was also associated with a higher risk of a child having emotional symptoms (RR: 1.29) and total difficulties (RR: 1.46).

The researchers noted that this association was not consistent among women who used acetaminophen after pregnancy (89%) or for their partner’s acetaminophen use (84%).

“Further studies are required to elucidate mechanisms behind this association as well as to test alternatives to a causal explanation. Given the widespread use of acetaminophen among pregnant women, this can have important implications on public health advice,” the authors stated. “However, the risk of not treating fever or pain during pregnancy should be carefully weighed against any potential harm of acetaminophen to the offspring.”


Stergiakouli E, Thapar A, Smith GD. Association of acetaminophen use during pregnancy with behavioral problems in childhood: evidence against confounding. JAMA Pediatr. 2016; doi:10.1001/jamapediatrics.2016.1775.