Is acetaminophen use when pregnant associated with kids' behavioral problems?

Acetaminophen is generally considered safe in pregnancy and is used by a many pregnant women for pain and fever.

Evie Stergiakouli, Ph.D., of the University of Bristol, United Kingdom, and coauthors analyzed data for 7,796 mothers enrolled in the Avon Longitudinal Study of Parents and Children between 1991 and 1992 along with their children and partners. The authors examined associations between behavioral problems in children and their mothers' prenatal and postnatal acetaminophen use, as well as acetaminophen use by their partners.

Questionnaires assessed acetaminophen use at 18 and 32 weeks during pregnancy and when children were 5 years old. Behavioral problems in children reported by mothers were assessed by questionnaire when children were 7 years old.

At 18 weeks of pregnancy, 4,415 mothers (53 percent) reported using acetaminophen and 3,381 mothers (42 percent) reported using acetaminophen at 32 weeks. There were 6,916 mothers (89 percent) and 3,454 partners (84 percent) who used acetaminophen postnatally. The study reports 5 percent of children had behavioral problems.

Study results suggest prenatal use of acetaminophen by mothers at 18 and 32 weeks of pregnancy was associated with increased risk of conduct problems and hyperactivity symptoms in children, and maternal acetaminophen use at 32 weeks of pregnancy also was associated with higher risk for emotional symptoms and total difficulties in children.

Postnatal maternal acetaminophen use and acetaminophen use by partners were not associated with behavioral problems. Because the associations were not observed in these instances, the authors suggest that this may indicate that behavioral difficulties in children might not be explained by unmeasured behavioral or social factors linked to acetaminophen use.

Study limitations include a lack of information on dosage or duration of acetaminophen use.

"Children exposed to acetaminophen use prenatally are at increased risk of multiple behavioral difficulties. ... Our findings suggest that the association between acetaminophen use during pregnancy and offspring behavioral problems in childhood may be due to an intrauterine mechanism. 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 write.

But the authors also caution: "However, the risk of not treating fever or pain during pregnancy should be carefully weighed against any potential harm of acetaminophen to the offspring."