Scientists have discovered that the use of painkillers during pregnancy in rats may reduce the fertility of their offspring.
The study shows that rats who were put on a course of paracetamol or prescription-only drug indomethacin gave birth to female offspring with fewer eggs, smaller ovaries, and who had smaller litters themselves.
The effects of the painkillers were even observed in the subsequent generation – the granddaughters of the initial test subjects were found to have smaller ovaries and altered reproductive function.
Male offspring also suffered the effects at birth showing smaller numbers of cells that give rise to sperm in later life. However, their fertility recovered to normal levels by the time they reached adulthood.
The scientists tested the effects of paracetamol over the course of nine days, and the effects of the indomethacin – a drug from the same class as aspirin and ibuprofen – over the course of four days.
The study, published in Scientific Reports, suggests that the painkillers change the way germ cells (which later differentiate into egg and sperm cells) develop in the womb. These drugs are known to alter hormones known as prostaglandins, which control ovulation, the menstrual cycle and the induction of labour.
Fetal development is slower in humans than it is in rats but these findings still hold significance due to the similarities between our species, said lead author Professor Richard Sharpe from the University of Edinburgh.
He stated: '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.'
The scientists said women should continue to follow the current NHS guidance around the use of painkillers in pregnancy, which is to take the lowest effective dose for the shortest possible time.
Professor Richard Anderson, a co-author of the study, also from the University of Edinburgh, added: '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.'