Better in their words…

The findings raise new questions about prenatal acetaminophen exposure, but researchers say the drug can still be used when medically needed.

Source: Tylenol Use During Pregnancy Linked to Reproductive Changes in Daughters | The Epoch Times

By George Citroner. 10/23/2026|Updated: 10/23/2026

Danish research raises concerns about the potential impact of a common pain medication during pregnancy.

Researchers in Denmark recently published findings in Human Reproduction Open suggesting that girls whose mothers took acetaminophen (Tylenol) during pregnancy had reproductive changes that may signal fertility risks.

Findings Flag Fertility Concerns

The study, led by Dr. Margit Bistrup Fischer at Copenhagen University Hospital, analyzed data from more than 300 baby girls and their mothers.

At 3 months, girls exposed to acetaminophen in the womb had ovaries that were 40 percent smaller, utereses that were 13 percent smaller, and 23 percent fewer ovarian follicles (the structures that contain immature eggs) compared with girls who were not exposed.

Why does follicle count matter? Fischer told The Epoch Times that girls are born with all the eggs they will ever have, and that the establishment of this ovarian reserve before birth is a “critical stage” of reproductive development. A smaller starting supply can, hypothetically, mean reduced fertility and earlier menopause later in life.

Those exposed during early pregnancy also showed lower levels of a hormone called anti-Müllerian hormone (AMH), also potentially indicating decreased fertility. In healthy women of childbearing age, higher levels of AMH mean that the ovaries have a larger supply of eggs.

Animal and laboratory models suggest that acetaminophen acts as an endocrine disruptor during gestation, which may then affect reproductive organ growth.

Researchers also followed up with girls during adolescence: exposed girls had smaller ovaries and uteruses.

This research adds evidence to a 2025 human cohort study that found prenatal exposure to acetaminophen was associated with impaired formation of primordial ovarian follicles, the tiny sacs that contain immature eggs, resulting in fewer ovarian follicles, smaller ovarian and uterine volumes, and lower reproductive hormones, all of which flag fertility concerns.

Daughters’ Fertility Not Assessed

Fischer said that long-term follow-up is needed to determine whether these early-life differences have any clinical significance later in life.

The study can’t predict outcomes for any one woman or child, and many mothers who used acetaminophen had daughters with entirely normal ovarian measurements.

The study also did not track whether any of these girls went on to have fertility problems or earlier menopause.

“Our study does not suggest that pregnant women should stop using Paracetamol (acetaminophen) when it is genuinely needed, particularly for fever or significant pain,” she said. However, Fischer said the findings add to growing concerns about acetaminophen use during pregnancy, particularly because the over-the-counter drug is often perceived as entirely risk-free.

Dosage Matters

Most mothers in the study took low doses of acetaminophen, primarily for headaches or muscle pain, and none exceeded the recommended daily limit of 4,000 milligrams.

Fischer said that alternative methods may be sufficient for pain relief in some cases, and that the majority of pregnant women in the study used acetaminophen for reasons other than fever or severe pain.

Christian De Geyter, a professor and a reproductive medicine specialist in Switzerland, said in a press statement that the findings underline the importance of weighing dose and duration during pregnancy. He also called for recommendations to be revisited and for the girls to be tracked into adulthood and menopause.

What Women Should Do

Current guidelines in Europe and the UK still list acetaminophen as the first-line pain reliever in pregnancy when needed, and it remains the only over-the-counter fever reducer approved for use during pregnancy in the United States.

Fischer said decisions about pain management should be made in consultation with healthcare providers, and that nondrug options may be suitable for some women.

Her own advice tracks existing recommendations: use medication during pregnancy only when clinically indicated, at the lowest effective dose and for the shortest necessary time. She noted in a press statement that most women in the study weren’t treating fever or severe pain, and that in those cases, “nonpharmacological approaches, such as rest, hydration, physiotherapy, exercise, heat treatment, or other supportive measures, may be sufficient if women receive appropriate counselling.”

Fischer said that many women in the study who used acetaminophen during pregnancy had daughters whose ovarian measurements were similar to those of daughters born to women who did not use the painkiller.

“We believe that pregnant women and healthcare professionals should be informed about the findings of our study,” she said. “So they can make informed decisions together.”

Separately, acetaminophen use in pregnancy has drawn regulatory attention for reasons unrelated to reproductive health. In September 2025, the Food and Drug Administration began a process to update the labeling of acetaminophen to include potential neurodevelopmental risks such as autism and attention-deficit/hyperactivity disorder.

The agency also issued a letter to healthcare providers nationwide to raise awareness about these potential risks.73Share this article

George Citroner

Author

George Citroner reports on health and medicine, covering topics that include cancer, infectious diseases, and neurodegenerative conditions. He was awarded the Media Orthopaedic Reporting Excellence (MORE) award in 2020 for a story on osteoporosis risk in men.