http://www.laleva.org/eng/2016/01/taking_paracetamol_while_pregnant_could_harm_your_daughters_fertility.html
Taking paracetamol while pregnant 'could harm your daughter's fertility': Study links popular painkiller to smaller ovaries and fewer eggs
- Female offspring had smaller ovaries and gave birth to fewer babies
- Prolonged use also causes levels of the hormone testosterone to plummet
- Medicines appeared to have a similar effect on subsequent generations
- Experts advise against prolonged use of the painkiller during pregnancy
Pregnant women who take common painkillers like paracetamol could unwittingly be putting the fertility of their daughters at risk, a study suggests.
Paracetamol is the most widely-used painkiller in the world - and is deemed the only painkiller that is safe for mothers-to-be.
But tests found when a mother took paracetamol or was prescribed the aspirin-like drug indomethacin, her female offspring had fewer eggs than those not exposed to the medicines.
Previous research by the same Scottish scientists found paracetamol had lifelong effects on baby boys, raising their risk of everything from infertility to cancer.
They say mothers-to-be have become 'blasé' about paracetamol's potential dangers – have and urged them to think twice before taking the drug.
If the tablets are taken, they should be used in the lowest possible dose, for the shortest possible time, they add.
The new research, which was performed on rats, found mothers given paracetamol had daughters with smaller ovaries and who gave birth to smaller litters of babies.
Males were affected too, having fewer cells that give rise to sperm later in life.
However, their fertility recovered to normal levels by the time they matured into adults.
Despite the fact that foetal development is slower in humans than in rats, the scientists say the findings are significant given the similarity of the two species' reproductive systems.
Paracetamol is widely used to treat headaches, while prescription-only indomethacin reduces inflammation and the pain of fever and arthritis.
Study co-author Professor Richard Sharpe, from the University of Edinburgh's MRC Centre for Reproductive Health, said: 'It's important to remember that this study was conducted in rats, not humans. However, there are many similarities between the two reproductive systems.
'We now need to understand how these drugs affect a baby's reproductive development in the womb so that we can further understand their full effect.'
Rats were given the drugs over several days and experienced effects after one to four days.
As well as affecting a mother's immediate offspring, the medicines also appeared to have an impact on subsequent generations.
Granddaughters of the animals given the painkillers while pregnant also had smaller ovaries and altered reproductive function.
Some painkillers may affect the development of 'germ cells' that mature into eggs and sperm within the womb, according to the study published in the journal Scientific Reports.
The reason could be that the drugs act on hormones called prostaglandins which are known to regulate ovulation, the menstrual cycle, and the induction of labour.
The Royal College of Midwives said mothers-to-be should seek medical advice before taking paracetamol at all.
Several studies have suggested it interferes with the development of the male reproductive system while still in the womb.
This is important because it is thought that if this programming goes wrong, it has lifelong effects, putting the child at higher risk of a range of problems from genital birth defects to infertility and testicular cancer.
Testosterone, which is made in the testicles, is thought to be key to the whole process, so the researchers carried out an experiment designed to show if exposure to paracetamol in the womb cuts levels of the hormone.
Experiments on babies in the womb would be impossible, so the researchers have previously studied mice that had pieces of human foetal testicular tissue grafted onto them.
The animals were given paracetamol in doses equivalent to those taken by people and the amount of testosterone they made was measured.
Taking paracetamol for just one day had no effect on testosterone levels.
However, treatment three times a day for seven days caused it to almost halve, the journal Science Translational Medicine reports.
A second test confirmed levels of the male sex hormone had plummeted.
The researchers urged pregnant women to follow existing NHS guidance, which is to take paracetamol for at the lowest effective dose for the shortest possible time.
Co-author of the latest study Professor Richard Anderson, said: 'These studies involved the use of painkillers over a relatively long period.
'We now need to explore whether a shorter dose would have a similar effect, and how this information can be usefully translated to human use.'
The work was funded by the Medical Research Council and the Wellcome Trust.
Professor Adam Balen, chairman of the British Fertility Society, said: 'This is an interesting study of long-term use of paracetamol in pregnant rats and so, whilst we must be cautious extrapolating to humans, it is sensible for pregnant women to minimise use of paracetamol and other painkillers and seek medical advice if they experience problems with significant pain in pregnancy.'
The Medicines and Healthcare products Regulatory Agency (MHRA), which issues guidance on medicines, said the study findings would be 'carefully evaluated'.
A spokesman said: 'Women should avoid taking medicines during pregnancy unless absolutely necessary and should speak to their doctor, midwife or pharmacist before doing so.
'Paracetamol is generally considered to be a safe treatment for pain relief during pregnancy but should be taken at the lowest possible dose for the shortest time.'