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Found in nearly every home, paracetamol (acetaminophen) is one of the world’s most widely used medicines. But what are the effects when it is taken during pregnancy? Here is a look at recent studies, including those raising questions about a possible link with autism.
Who hasn’t slipped a pack of paracetamol into their bag or medicine cabinet? As the pain reliever and fever reducer most of us rely on, paracetamol is a daily fixture, especially for pregnant women, who are often advised to avoid many other medications. Yet this familiar gesture conceals an important question: is paracetamol use during pregnancy truly safe for the unborn child?
For about a decade, researchers have been investigating the potential risks of paracetamol taken during pregnancy. Their focus has been especially on possible effects on fetal brain development, to the point that some experts now wonder whether paracetamol should be considered an endocrine disruptor. Several large-scale population studies have explored potential correlations between paracetamol use by pregnant women and the long-term health of their children.
These investigations draw on vast cohorts, collecting detailed data on medication exposure through questionnaires or prescription records, then comparing that with children’s health outcomes, including results from medical examinations and birth defect registries. The main research focus has been on three systems: the nervous system (behavioral issues, attention deficit, autism spectrum disorders), the respiratory system (asthma and wheezing), and the reproductive system (malformations). But despite the ever-increasing number of studies, the scientific community has yet to reach consensus. Results not only differ but sometimes directly contradict each other. Much of this inconsistency stems from the inherent limitations of population studies: most fail to specify the exact dosage, how long the medication was used, or during which trimester it was taken. As a result, it remains difficult to determine whether a single dose has the same potential impact as prolonged use. Variations in how data are collected further complicate any attempt to compare findings or create a comprehensive overview.
Associations and Causality: Where Does the Science Stand?
A recent Harvard-led meta-analysis, reviewing data from 46 studies, reported evidence of an association between prenatal paracetamol exposure and neurodevelopmental disorders, particularly when use lasted more than four weeks. However, the researchers themselves emphasize that association does not mean causation. There are many possible sources of bias in these studies, including recall bias and measurement error. In addition, criteria for diagnosing autism have evolved over time, with a broader spectrum now recognized, making comparisons between studies from different periods especially tricky. Some cases that might have gone unnoticed in the past are now routinely identified, altering perceptions of risk.
Because of these uncertainties, scientists are calling for more detailed and precise information on paracetamol prescriptions, self-medication, dosage, and length of exposure. They also highlight the need to account for genetic factors, now widely recognized as major contributors to autism risk. A Swedish study that examined data from nearly 2.5 million children found only a weak association between maternal paracetamol use during pregnancy and later diagnosis of autism or ADHD. When researchers compared siblings, the link disappeared, suggesting that genetics or shared family environment, rather than the medication itself, may explain the observed association.
To get around the limitations of epidemiological studies, researchers also rely on experimental models, using both cell cultures and laboratory animals to investigate possible direct and long-term effects of paracetamol exposure. Yet here, too, the findings diverge. No animal model can truly replicate human biology, and the doses administered to animals often far exceed those used in routine clinical practice.
For example, in studies with mice, some behavioral changes have been observed after paracetamol exposure, but there is no evidence these findings translate into autism spectrum disorders in humans. To date, the most recent data indicate no harmful neurological effects at standard therapeutic doses. Even new in vitro screening tools, designed to detect neurotoxicity, have not shown evidence of acute toxicity from paracetamol, though the possibility of subtle long-term effects still requires more research.
Prudent Guidance, Not Panic
As the scientific debate continues, experts stress the importance of moving beyond both complacency and alarmism. Health agencies and NGOs have stepped up information campaigns, particularly targeting pregnant women. The prevailing advice follows the precautionary principle: paracetamol should only be used at the lowest effective dose and for the shortest period needed. Importantly, this guidance is meant to avoid making expectant mothers feel guilty or pushing them toward riskier alternatives such as nonsteroidal anti-inflammatory drugs, which are known to be dangerous after the sixth month of pregnancy.
Across the scientific and medical communities, there is agreement that paracetamol remains a valuable medication for treating pain or fever. Both of these symptoms, if left unmanaged, can themselves be harmful to the fetus. Ultimately, only careful, medically guided use ensures a safe balance between benefit and risk. For now, vigilance is essential, but panic is not.
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