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Just about every woman who becomes pregnant develops a headache, a backache, muscle pain or fever. In North America, more often than not pregnant women will reach for Tylenol to relieve mild everyday pain. But a new study suggests that taking Tylenol or other products made with acetominophen (a chemical known as paracetamol outside of the United States) during pregnancy can affect the child's future development of language skills and social abilities.
For 10 years, from 1999 to 2008, the Norwegian national health system asked every pregnant woman in Norway to participate in the Norwegian Mother and Child Cohort Study. By the end of the study, the mothers of 48,631 children had returned survey data on their pregnancies and their lifestyle choices during the first three years of their children's lives. Among the children, there were 2,919 children who had a same-sex brother or sister. The researchers looked at the survey data sent in by the mothers of these children to determine whether using drugs that contain acetominophen had any effect on mothers' or children's wellbeing.
The researchers found that children of mothers who had used acetominophen on 28 days or fewer during pregnancy had children who had poorer motor coordination skills than their siblings who had not been exposed to Tylenol-like medications in the womb. When mothers took Tylenol for more than 28 days during pregnancy, their children displayed:
- Higher activity levels, that is, they were more likely to be on track for a diagnosis of ADHD,
- Poorer communication skills,
- Poorer internalizing behavior, that is, "learning the rules" and caring about others,
- Poorer externalizing behavior, that is, exploration, curiosity, and seeking new experiences,
and also poorer motor coordination skills.
The researchers found that the more often a mother took Tylenol or similar acetominophen mediations during pregnancy, the worse the developmental problems in their children by age three. Nearly 65% of Norwegian mothers took acetominophen at least once during pregnancy. A little under 5% took acetominophen on 28 days or more, and some mothers used the "harmless" pain reliever up to 7 times a day.
The study did not find similar effects from ibuprofen.
Since the developmental problems found in this study, some laypeople reading news stories about the research have quoted its scientists as having said that taking Tylenol during pregnancy causes autism. Harvard autism researcher Dr. Martha Herbert disagrees, noting that while many mothers to be pop a Tylenol whenever they feel an ache or pain coming on ""I don't think it's a done deal," she told Reuters Health. In the Norwegian study, children were not diagnosed with autism by age 3, and it is possible there are many other factors also involved, according to Dr. Herbert.
But this does not mean it's safe to use common pain relievers during pregnancy, either. The authors of the study of Norwegian mothers note that nearly all mothers use some kind of pain reliever during pregnancy, especially acetaminophen,aspirin, ibuprofen, docusate, naproxen, and pseudoephedrine, and of the 54 over the counter pain relievers that have been tested for their effects on the developing embryo and fetus, only two have been found to be unequivocally safe.