Use of analgesics such as acetaminophen, aspirin and ibuprofen during pregnancy may partly account for a sharp increase in male reproductive disorders in recent decades, according to a study.
The research found that women who took a combination of more than one mild analgesic during pregnancy had an increased risk of giving birth to sons with cryptorchidism.
Cryptorchidism has been found to affect as many as 1 in 11 Scandinavian boys, although rates vary from 2 to 9% in various Scandinavian countries.
The study found that the risk of cryptorchidism was especially increased during the second trimester.
Pregnant women on painkillers
The researchers from Finland, Denmark and France, whose work was published in the November issue of Human Reproduction, said more studies were urgently needed and advice to pregnant women on use of painkillers should be reconsidered.
"Women may want to try to reduce their analgesic use during pregnancy," said Dr Henrik Leffers of Copenhagen's Rigshospitalet, who led the research. "However, as biologists this is not something we can advise women about. So we recommend that pregnant women seek advice from their physician."
According to Dr Leffers' team, more than half of pregnant women in Western countries report taking mild analgesics.
Sperm counts have fallen
Research in developed nations has shown that sperm counts have fallen by about 50% in the past half century.
The prospective cohort study looked at two groups of women, 834 in Denmark and 1,463 in Finland, who were questioned about their use of medication during pregnancy.
Their male babies were examined at birth for any signs of cryptorchidism. The study was supported by work by researchers in Denmark and France who found anti-androgenic effects in rat models.
These researchers said the effect of analgesics on rats was comparable with that caused by similar doses of known endocrine disrupters such as phthalates - a family of chemical compounds used in the manufacture of plastics such as PVC.
The results of the human study showed that women who used more than one analgesic simultaneously had a seven-fold increased risk of giving birth to sons with some form of cryptorchidism compared with women who took nothing.
The second trimester appeared to be a particularly sensitive time, with simultaneous use of more than one painkiller during this period linked to a 16-fold increase in risk.
"Although we should be cautious 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," Dr Leffers said.
Commenting on the findings, Dr Allan Pacey of Britain's Academic Unit of Reproductive and Developmental Medicine at Sheffield University said they were "somewhat alarming."
"It is worth noting the researchers found a significant difference when women had used painkillers for two weeks or more and that the impact was greatest when taking them during their second trimester. Clearly further research is needed as a matter of priority," he said in an emailed comment. (Reuters Health/November 2010)
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