Two-thirds of American women take acetaminophen for the aches and pains of pregnancy, but the medication might not be as benign as thought.
New research shows that women who took acetaminophen, best known as Tylenol, at the end of their pregnancies were much more likely to have child with attention-deficit/hyperactivity disorder (ADHD) or autism.
After testing blood from the mother and the umbilical cord soon after birth, the odds of these developmental disorders were more than twice as high in children exposed to acetaminophen near the time of birth. The association was strongest between exposure to acetaminophen and ADHD in the child.
Two previous studies have suggested a connection between acetaminophen in pregnancy and ADHD and autism in children. But those studies were based only on the mothers' memory of taking acetaminophen.
Those studies, when combined with the latest one, show "that prenatal acetaminophen use is consistently associated with an increased risk of developmental disabilities, including ADHD and possibly [autism]," said senior study author Dr. Xiaobin Wang. She's the director of the Center on the Early Life Origins of Disease at Johns Hopkins University Bloomberg School of Public Health, in Baltimore.
It's important to note that while the study found an association between an expectant mother's use of acetaminophen and the development of ADHD and possibly autism in her child, it cannot prove a definitive cause-and-effect link.
Wang said more research is needed. She said that she was not aware of any safe alternative drugs for pain or fever relief in pregnancy.
Acetaminophen has been shown to cross the placenta during pregnancy. That means if an expectant mom takes acetaminophen, some of the drug gets into the baby's system.
In rats, acetaminophen during pregnancy appeared to affect brain cells and certain hormone levels, which could disrupt brain development, according to background information in the study.
There were almost 1,000 children in this new study. Their average age was 10 and slightly more than half were boys.
Nearly 26% of the children had ADHD only. Close to 7% had autism, while 4% had both ADHD and autism. Just over 30% had another developmental disability. Almost 33% had no developmental concerns.
Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Cohen Children's Medical Center, in New Hyde Park, N.Y., is familiar with the findings.
"Although acetaminophen is a very safe and effective medication when taken as recommended in general, it may not be as safe as presumed if it is taken during pregnancy," he said.
"Since we do not know when during pregnancy the neurodevelopmental risks of acetaminophen exposure are greatest, it is hard to counsel pregnant women as to when they may safely take this medication without increasing the likelihood of their child having ADHD or [autism]," he added.
Adesman said pregnant women should talk with their health care provider before taking acetaminophen.
The findings were published online Oct. 30 in JAMA Psychiatry.
Learn more about what medications to avoid when you're pregnant from Consumer Reports.