Acetaminophen, the active ingredient in Tylenol and the only over-the-counter pain and fever reliever recommended for pregnant women, is not associated with an increased risk of autism or ADHD in children, according to two new studies. However, the research also indicates a potential link to future fertility issues in female offspring.
The first analysis, published in JAMA Internal Medicine, examined health records from over 120,000 children. Researchers found no association between prenatal acetaminophen exposure and autism diagnoses. A separate analysis of data from approximately 100,000 children also revealed no increased risk of ADHD diagnoses for those whose mothers used acetaminophen during pregnancy.
Researchers involved in the first study emphasized that avoiding acetaminophen for fever or pain during pregnancy could lead mothers to use less safe alternatives or experience complications such as preterm labor and miscarriage. They concluded that acetaminophen remains a safe and essential medication for pregnant individuals.
In contrast, a second study published in Human Reproduction Open, conducted by researchers at Copenhagen University Hospital, investigated potential impacts on reproductive health. This study found that infant girls whose mothers took acetaminophen during pregnancy had smaller ovaries, uteruses, and fewer ovarian follicles as infants. These girls also exhibited lower levels of reproductive hormones.
Researchers noted that while animal studies have shown impaired ovarian follicle formation can lead to reduced fertility, the implications of these findings for human fertility remain unknown and require long-term follow-up. The study authors cautioned that pregnant individuals should not be alarmed by the results, as the study identified associations rather than direct causation, and the outcomes for individual women and children are unclear. They stressed that the research does not provide evidence that prenatal exposure definitively affects future fertility or the age of menopause.
Acetaminophen is widely used, being the active ingredient in Tylenol and other common over-the-counter medications for cold, flu, and pain relief. The studies come at a time when diagnoses of autism and ADHD are on the rise in the United States. Current CDC figures indicate that approximately seven million American children were diagnosed with ADHD in 2022, an increase from six million in 2016. Recent data also shows a significant surge in first-time ADHD diagnoses among adults aged 30 to 64 between 2021 and 2024.
The researchers recommend that pregnant individuals discuss their use of acetaminophen with their healthcare provider.