Summary: Researchers in the Illinois Kids Development Study found an association between higher maternal acetaminophen use during pregnancy—most notably in the second trimester—and modest increases in attention and behavior difficulties observed in children at ages 2, 3, and 4. The prospective study tracked prenatal medication use and measured early childhood attention and behavioral outcomes using standardized caregiver reports.
Although acetaminophen is widely regarded as the safest over-the-counter analgesic and fever reducer for pregnant people, this research contributes to growing concern about potential links between prenatal acetaminophen exposure and neurodevelopmental effects. The authors emphasize that the results indicate trends in attention-related behaviors rather than formal diagnoses, and they call for additional research to confirm and clarify the findings.
Key Findings:
- Frequent acetaminophen use during pregnancy—especially in the second trimester—was associated with higher scores on attention-problem and externalizing-behavior scales in early childhood.
- The study evaluated over 300 children at age 2, with follow-up assessments at ages 3 and 4, showing consistent trends toward more attention- and behavior-related difficulties among those with higher prenatal exposure.
- These results add to earlier studies suggesting developmental risks related to prenatal acetaminophen, but larger and more diverse studies are still needed to reach strong causal conclusions.
Source: University of Illinois
Overview
A new analysis from the Illinois Kids Development Study (IKIDS) links increased acetaminophen use during pregnancy with small but measurable increases in attention and behavioral problems in toddlers and preschoolers. Results reported in the journal Neurotoxicology and Teratology show the most consistent associations when exposure occurred in the second trimester.
IKIDS is a prospective birth cohort led by investigators at the University of Illinois Urbana-Champaign that examines how environmental exposures during pregnancy influence child development. For this analysis, pregnant participants reported acetaminophen use at six time points across pregnancy—roughly every four to six weeks—providing a more detailed exposure timeline than studies that collect information only once per trimester.
Caregivers completed the Child Behavior Checklist (CBCL) for ages 1.5–5 when children were 2, 3, and 4 years old. The research team evaluated the relationship between prenatal acetaminophen use and scores on the Attention Problems and ADHD Problems syndrome scales, as well as Internalizing, Externalizing, and Total Problems composite scores.
More than 300 children were assessed at age 2, 262 were assessed at age 3, and 196 at age 4. The investigators observed that increasing acetaminophen use during pregnancy—particularly during the second trimester—was associated with higher Attention Problems and ADHD Problems scores at ages 2 and 3 and with elevated Externalizing and Total Problems scores at multiple ages.
Lead author Megan Woodbury, who completed the research as a graduate student at the University of Illinois and is now a postdoctoral researcher at Northeastern University, noted that the results point to consistent patterns in attention-related and externalizing behaviors. Susan Schantz, comparative biosciences professor emerita and principal investigator for IKIDS, cautioned that these differences do not equate to formal diagnoses such as ADHD but do reflect more frequent attention challenges and behavioral difficulties compared with less-exposed peers.
Examples of behaviors reported by caregivers included difficulty staying seated, trouble waiting turns, talking out of turn, reduced attention during tasks, and occasional aggression toward peers. The authors stress that these observations reflect group-level differences in early childhood behaviors rather than individual diagnostic outcomes.
Woodbury, who is pregnant herself, emphasized the importance of balanced messaging: severe pain, high fever, or other conditions that threaten maternal or fetal health may require acetaminophen use. At the same time, she and the research team suggest limiting nonessential use of acetaminophen during pregnancy until more is known about timing and dosage-related risks.
Limitations of the study include a cohort that is predominantly white, non-Hispanic, and of higher socioeconomic status, which may limit generalizability. The IKIDS team is working to expand recruitment to include participants from more diverse racial, socioeconomic, and geographic backgrounds to better understand how these findings apply across populations.
Funding
This research was supported by the Children’s Environmental Health and Disease Prevention Research Center funded by the National Institute of Environmental Health Sciences (NIEHS) and the U.S. Environmental Protection Agency, as well as the NIH Environmental Influences on Child Health Outcomes (ECHO) program.
About this research
Author: Diana Yates
Source: University of Illinois
Contact: Diana Yates – University of Illinois
Image credit: Neuroscience News
Original research (open access): “The relationship of prenatal acetaminophen exposure and attention-related behavior in early childhood” by Susan Schantz et al., Neurotoxicology and Teratology. DOI: 10.1016/j.ntt.2024.107319
Abstract (concise)
Acetaminophen is currently the most commonly recommended analgesic for use throughout pregnancy, yet emerging studies suggest prenatal exposure may be associated with altered neurodevelopment. Using prospective exposure data from 535 mother–infant pairs enrolled between December 2013 and March 2020, this analysis examined self-reported acetaminophen use at six time points in pregnancy and CBCL scores at ages 2–4. Higher acetaminophen exposure in the second trimester was linked to elevated Attention Problems, ADHD Problems, Externalizing Behavior, and Total Problems scores at ages 2 and 3, with some associations persisting at age 4. Cumulative exposure across pregnancy was also related to higher Attention Problems and ADHD Problems at ages 2 and 3. These findings suggest that prenatal acetaminophen exposure—especially during the second trimester—may be associated with early childhood attention-related behaviors, highlighting the need for further research on timing, dose, and long-term outcomes.