There are plenty of medications pregnant women are advised to avoid, but over-the-counter pain relievers like Tylenol and Advil are not among them. Now new research published online Monday in the journal Human Reproduction suggests that mild painkillers such as aspirin, acetaminophen (the active ingredient in Tylenol) and ibuprofen (the active ingredient in Advil and Motrin) may be linked to an increase in male reproductive disorders.
No need to toss those bottles yet; though intriguing, the overall number of women whose babies had problems is small. Even the researchers aren’t recommending pregnant women completely stop popping painkillers. (More on Time.com: 5 Pregnancy Taboos Explained (or Debunked))
The scientists from Denmark, Finland and France found that women who either took a combination of mild analgesics during pregnancy or took them during the second trimester of pregnancy had a greater risk of giving birth to baby boys with undescended testicles, a condition known as cryptorchidism, which may forecast poor semen quality and testicular cancer.
Specifically, the researchers found that women who used more than one painkiller at the same time had a seven-fold increased risk of having sons with some form of cryptorchidism in comparison with women who took no analgesics. In the second trimester, any painkiller use more than doubled the risk of cryptorchidism, and simultaneous painkiller use increased the risk 16-fold. (More on Time.com: Safety Issues: Pills During Pregnancy).
The scientists also pointed to work conducted on rats by two of the researchers who found that analgesics toyed with androgen production and led to decreased levels of testosterone when male fetal organs were forming. Researchers aren’t sure why that happens.
“If exposure to endocrine disruptors is the mechanism behind the increasing reproductive problems among young men in the Western world, this research suggests that particular attention should be paid to the use of mild analgesics during pregnancy, as this could be a major reason for the problems,” says Henrik Leffers, a senior scientist at the Rigshospitalet in Copenhagen who led the research. (More on Time.com: Study: IVF Causes Higher Rates of Baby Boys)
Taking painkillers presents more of a risk than known endocrine disruptors such as phthalates, say the researchers. Perhaps, they posit, painkiller use on top of exposure to phthalates could be associated with the increase in cryptorchidism. “Although we should be cautious about any over-extrapolation or over-statement, the use of mild analgesics constitutes by far the largest exposure to endocrine disruptors among pregnant women, and use of these compounds is, at present, the best suggestion for an exposure that can affect a large proportion of the human population,” says Leffers.
One 500-mg Tylenol tablet, says Leffers, will, “for most women, be at least a doubling of the exposure to the known endocrine disruptors during the pregnancy and that dose comes on a single day, not spread out over nine months as with the environmental endocrine disruptors.” (More on Time.com: Top 10 Pregnant Performers)
But Virginia Lupo, chair of the department of obstetrics and gynecology at Hennepin County Medical Center in Minneapolis and a maternal-fetal medicine specialist, cautioned against jumping to conclusions. “You’re looking at 13 women who took pain meds in the second trimester and had a son with this problem,” says Lupo. “This is not nearly enough data to say that women should avoid mild pain relievers in the second trimester.”
To reach their conclusions, researchers studied 834 pregnant women in Denmark and 1,463 in Finland, who either answered written questionnaires about their use of medication during pregnancy and/or responded to a telephone interview. Interestingly, the data revealed that women under-reported their use of painkillers in the written questionnaire: of the 298 Danish moms who responded via questionnaire and phone interview, 31% reported using painkillers in the questionnaire while 57% reported that in the interview. (More on Time.com: Health Check-Up: Women & Health)
Taking painkillers appeared to have no effect on the babies delivered to the women in Finland, where 2% of infant boys are born with undescended testicles. In Denmark, that number jumps to 9%. Denmark has witnessed a significant increase in cases of cryptorchidism, from less than 2% 50 years ago. There haven’t been many studies examining rates in the U.S., but one conducted at Mount Sinai Hospital in New York found that nearly 4% of 6,935 boy babies born between 1987 and 1990 had undescended testicles.
What’s clear, say the European researchers, is that more study is needed. In the meantime, they advise pregnant women to cut back on the analgesics, talk to their doctors, and, recommends Leffers, “in general follow the advice to use as little medicine during pregnancy as possible.”
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