Taking the pain medication acetaminophen, also known under the brand name of Tylenol, during pregnancy may be associated with child behavioral issues at three years old.
That's according to a new report published in the journal PLOS Medicine.
"Acetaminophen is commonly used during pregnancy to treat a variety of ailments, but evidence is emerging that shows acetaminophen may be associated with developmental concerns among children," said lead author Kristin Sznajder, assistant professor of public health sciences at Penn State College of Medicine.
"Our research found that acetaminophen use during pregnancy increased the risk for attention and sleep problems among young children by more than 20%," she told Fox News Digital.
Here are more details.
What is acetaminophen?
Acetaminophen is often taken as an over-the counter medication to reduce pain and fever, according to the U.S. Food & Drug Administration (FDA).
It's also a prescription medication.
The FDA notes that acetaminophen "is found in hundreds of medicines including those used for colds, flu, allergies and sleep."
Approximately 65%-70% of pregnant women have reported using the pain medication during pregnancy, according to multiple reports.
"Although acetaminophen has been shown to cross the placental barrier and therefore may directly impact fetal development, the mechanisms of action for the effect of acetaminophen on fetuses are unknown," the study said.
The researchers from Penn State reviewed data from the First Baby Study, which is a prospective study designed to examine the impact of a mother’s mode of delivery on childbearing by following more than 3,000 women who delivered babies from 2009 to 2011 in multiple hospitals in Pennsylvania.
For this study, the researchers studied 2,423 mother-child pairs, in which women completed a "prenatal stress inventory" and reported their medication use during their third trimester.
The study's methods
The participants were asked what prescription and non-prescription medications (other than vitamins) that they took occasionally during pregnancy.
When their child turned three years old, they completed the Child Behavior Checklist (CBCL), which "has been widely used in studies of neurodevelopmental and behavioral outcomes in young children," per the study.
The women completed the 99-item CBCL questionnaire that asked them to rate their child using a three-point scale on a variety of behaviors, such as restlessness, avoiding eye contact and not wanting to sleep alone.
The mothers were interviewed at baseline to evaluate for depression and the level of stress during pregnancy.
The results of the study
The study found that approximately 42% participants reported using acetaminophen during pregnancy, with a third of women going through labor induction and 29.4% undergoing a Cesarean delivery.
The women who used acetaminophen were also more likely to have consumed alcohol during pregnancy, have private insurance and be non-Hispanic white.
These women were more likely to be diagnosed with anxiety or depression before their pregnancy and were more likely to report high levels of stress during their pregnancies.
They were also more likely to have ingested other non-prescription drugs in addition to acetaminophen, compared with women who did not take acetaminophen.
When the study analyzed the data without controlling for confounding variables, it found "acetaminophen use was associated with higher scores in three areas: [children who are] withdrawn, [have] sleep problems and [have] attention problems."
But after the study accounted for variables that could confound the results — such as stress during pregnancy — the researchers found the children of women who used acetaminophen during pregnancy were significantly more likely to have sleep problems and attention problems compared to the children of women who did not take acetaminophen during pregnancy.
The authors noted that the association between acetaminophen use and adverse child behavioral outcomes was "mitigated" after controlling for the participants’ stress — which suggests that stress and the use of acetaminophen may independently affect behavioral outcomes in children.
The study's limitations
The study noted several limitations, including not determining the dose or frequency of use of acetaminophen among the participants’ pregnancy and also not stratifying the use of acetaminophen by trimester.
The researchers may have also underestimated acetaminophen use among the participants because the women were only asked about their medication history at one time period during their pregnancy.
The study also only assessed the child’s behavior via the mother's observations and impressions — and not via a trained psychologist.
This study concluded in its findings "an association between acetaminophen use and child behavioral problems at the age of three years."
Health care professionals should balance the benefits with the risks in recommending acetaminophen during pregnancy, the authors suggested.
Is acetaminophen safe to use during pregnancy?
The FDA is aware of previous research that has shown an association between acetaminophen and the risk of attention deficit hyperactivity disorder (ADHD) in children born to women who took the pain medication during pregnancy.
The agency reviewed the research — but because of potential limitations in design and sometimes conflicting results, it has not found a reliable conclusion, according to its website.
"Pregnant women should always consult with their health care professional before taking any prescription or OTC medicine," the FDA said.
"Women taking pain medicines who are considering becoming pregnant should also consult with their health care professionals to discuss the risks and benefits of pain medicine use."