The research, published in Science Translational Medicine, demonstrated that extended use of acetaminophen by expecting moms lowered the production of testosterone in incubating male babies.
The study didn't use humans, but rather mice that carried grafts of human tissue. (That procedure isn't unusual, particularly in obstetrical studies for which using humans could be unethical—but it's not the gold standard of research, either.) After one day, there was no effect on testosterone production in the animals exposed to the drug. But after a full week, the amount of the hormone went down almost by half—a noteworthy finding because reduced testosterone has been linked to adverse outcomes like higher chances of infertility and testicular cancer.
This isn't the first time that the painkiller has been implicated in studies that seem to suggest potentially bad health outcomes. Another recent report suggested links to autism and ADHD.
Nathaniel G. DeNicola, M.D., an ob-gyn affiliated with the University of Pennsylvania, says that he's not alarmed by the most recent study. "There's really no definitive risk. In absolute terms, the risk is still very low," he told Parents.com. "We look for a preponderance of evidence, or a meta-analysis of many studies. It's important to continue the research, but from where the evidence stands right now, it's not enough to say, 'This is a dangerous medication.'"
This new research doesn't suggest that pregnant women shouldn't take acetaminophen at all, he said, adding, "It can be very useful for pain management and to reduce fevers. As long as we take it judiciously, it's still something that is recommended in pregnancy."
And because of that, he's not recommending any change at all—regardless of whether a pregnant women is expecting a baby boy or a baby girl.
In fact, the bigger danger, he says, would be for expecting moms to respond to this study by ditching the drug out of fear and opting instead for an NSAID like Motrin, which is not recommended in pregnancy. "As classes of medications go, [acetaminophen] is still one of the preferred options," he says
In general, doctors feel more comfortable with pregnant patients taking medication after the vulnerable first trimester. But if you're still concerned about taking any kind of medication for pain, Dr. DeNicola suggests nonmedical options that can provide relief as well, including massage therapy and prenatal yoga classes, as well as wearing a pelvic girdle, which can be useful in relieving some of the pain caused by pressure from the uterus late in the third trimester.
But the bottom line regarding acetaminophen and pregnany—at this point, anyway—is the same as it has long been, he says. "The classic line we often use in medicine is, 'It's not enough to change what we do.' We keep the same recommendation: lowest dose, shortest amount of time."
I took Tylenol sparingly in my own twin pregnancy, and I'm reassured—though not surprised—to hear a professional respond without alarm to this latest study.
But does the latest research change the way you view painkillers in pregnancy?
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