July 10, 2026
There is no statistically significant evidence that taking acetaminophen, also known as Tylenol, during pregnancy has a negative impact on how early a child is born or a child’s weight at birth, according to new research led by environmental scientists at the UNC Gillings School of Global Public Health
A new study, published recently in the American Journal of Epidemiology, looked at a large group of pregnancies in the United States in a National Institutes of Health (NIH) program and found that acetaminophen use during pregnancy did not have a significant impact on gestational age (how early a child is born) or average birth weight. Interestingly, when birth weight accounted for when the child was delivered — classified by being small-for-gestational-age (SGA) or large-for-gestational-age (LGA) — the study did find an association between acetaminophen use during pregnancy and lower odds of a child being born large for their gestational age.
Dr. Rebecca Fry
“Given the widespread use of acetaminophen, these findings offer important reassurance about its safety with respect to birth timing and infant size,” said senior author Rebecca Fry, PhD, the Carol Remmer Angle Distinguished Professor and chair of environmental sciences and engineering
Acetaminophen is widely used during pregnancy to treat pain and fever. It is one of the few over-the-counter pain-relieving medications approved for use during pregnancy, but recent research has shown mixed results about whether it may affect fetal development or impact birth size and timing. The study aimed to add more evidence to this discussion by directly examining the associations between acetaminophen use and birth health.
The research team, led by Fry and first author Katelyn Huff, PhD, postdoctoral researcher at the Gillings School, studied more than 8,900 mother-infant pairs enrolled in the NIH’s Environmental influences on Child Health Outcomes (ECHO) program. The study analyzed the relationship between acetaminophen use during pregnancy and four important indicators of child health at birth: (1) preterm birth, (2) birth weight, (3) SGA size and (4) LGA size.
Around 59% of mothers in the ECHO study reported using acetaminophen during their pregnancy. Following analysis, the researchers found that prenatal acetaminophen use was associated with lower odds of LGA. They found no association with preterm birth, birth weight or SGA
The results offer reassurance for pregnant people who use acetaminophen as directed, though the authors note that more research is still needed on dosing, timing and other possible health effects. While typical acetaminophen use during pregnancy did not appear to raise birth risks in this study, it is still important to talk with your doctor about use of acetaminophen, as well as any other medication, during pregnancy.
Read the full study online
Contact the UNC Gillings School of Global Public Health communications team atsphcomm@unc.edu
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The Center for Environmental Health and Susceptibility (CEHS) has received a 5-year, $7.7M award from the National Institute of Environmental Health Sciences. This grant supports research and community engagement to improve environmental health and well-being for people in North Carolina and across the nation
