New Study Links Pregnant Women Taking Acetaminophen with Language Delays in Baby Girls

From TIME - January 10, 2018

Two-year-old girls whose mothers took acetaminophen during their pregnancies had higher rates of language delays compared to those whose mothers did not, finds a new study. Similar delays were not seen in boys, who generally develop language skills more slowly than girls.

The study, published in the journal European Psychiatry, included 754 Swedish women who were interviewed between weeks 8 and 13 of their pregnancies. The women answered questions about how often they had used acetaminophenan over-the-counter pain and fever reliever, sold as Tylenol in the United Statessince they had conceived. They also provided urine samples, which were tested for acetaminophen concentration.

The researchers then compared womens acetaminophen use with their childrens scores on a language-development screening given to all children in Sweden at 30 months, along with the mothers personal assessments of their childs language use. Children who used fewer than 50 words at this age were considered to have a language delay.

Acetaminophen use during early pregnancy was common, the researchers found: 59% of women reported taking it at least once in their first trimester, and some reported taking up to 100 pills in that time. For their primary analysis, they compared women with high exposurethose who took acetaminophen more than six times since becoming pregnantwith women who reported taking none at all.

Overall, about 10% of children in the study had a language delay at 30 months, with boys having greater delays than girls. But girls born to mothers in the high-acetaminophen group were nearly six times more likely to have language delays than girls whose mothers had used none. The more tablets women reported taking, and the higher the levels detected in their urine, the more likely their daughters were to have language delays.

There was no significant difference in language delays between boys whose moms took acetaminophen and those whose moms did not. In fact, women with higher urine concentrations of acetaminophen during pregnancy were slightly less likely to have sons with language delays.

The researchers cant say for sure why acetaminophen during pregnancy seems to affect male and female fetuses differently, and they stress that their study was only designed to find associations, not a cause-and-effect relationship.

But they do offer one possible theory. Girls around 30 months tend to have higher vocabularies than boysa well-recognized female advantage in early-childhood language development, they write in their study. Taking acetaminophen during pregnancy, the authors say, may diminish that advantage.


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