London - Pregnant women have been warned that taking paracetamol could harm their unborn baby boys.
The popular painkiller is believed to affect testosterone production, raising the risk of boys developing problems ranging from infertility to cancer.
Researchers from Edinburgh University have warned that Britons are too “blasé” about paracetamol’s potential dangers – and urged pregnant women to think twice before taking the drug.
They said that if the pills are taken, they should be used in the lowest dose for the shortest possible time. And the Royal College of Midwives has advised mothers-to-be to seek medical advice before taking paracetamol at all.
The drug, which is the most widely used painkiller in the world, is the only one which has been deemed safe to take during pregnancy, and is used by many mothers-to-be.
However several studies have suggested that it interferes with the development of the male reproductive system while still in the womb – putting the child at higher risk of a range of problems, from genital birth defects to infertility and testicular cancer.
Because of the difficulties of conducting experiments on babies in the womb, the researchers decided to graft human foetal testicular tissue onto mice.
The animals were then given doses of paracetamol, and the amount of testosterone they produced was measured to see if exposure to paracetamol in the womb cut their levels of the hormone.
The study found that taking paracetamol for just one day had no effect on their testosterone levels.
But taking the drug three times a day for a week caused their levels of the hormone to almost halve.
Writing in the journal Science Translational Medicine, the researchers urged pregnant women to take paracetamol at the lowest dose and for the shortest possible time.
Dr Rod Mitchell, the study’s lead author, said that while he doesn’t want mothers-to-be to be in unnecessary pain, he is concerned that paracetamol is often taken “without a second thought”.
His co-author Professor Richard Sharpe said many people have become “blasé” over the pill’s use. He advised pregnant women in need of long-term pain relief to speak to their doctor about whether the benefits of paracetamol outweigh the risks.
Professor Sharpe stressed that it wasn’t his intention to scare pregnant women, but to arm them with information that will empower them, allowing them to give their child the best start in life.
And he pointed out that the research purely applies to baby boys in the womb.It doesn’t have any implications for female foetuses or for men taking paracetamol.
The drug safety watchdog, the Medicines and Healthcare Products Regulatory Agency, said: “The findings of this new study will be carefully evaluated to determine whether it has any implications for the safe use of paracetamol.”
The Royal College of Paediatrics and Child Health said that low doses of paracetamol are sometimes necessary to treat fevers that can damage the developing baby.
But Carmel Lloyd, from the Royal College of Midwives, said: “Ideally, women should avoid taking medicines when they are pregnant, particularly during the first three months.’
She added: “Minor conditions such as colds or minor aches and pains often do not need treating with medicines.
“If women feel they need to take medicines such as paracetamol when they are pregnant, they should talk to their midwife or doctor first.”
Daily Mail