Paracetamol considered safest pain relief in pregnancy
PARACETAMOL is widely considered the safest pain relief during pregnancy.
Routinely used during all stages of pregnancy to reduce a high temperature and for pain relief, no definitive evidence has been found to date that it has any harmful effects on the unborn baby.
NHS Choices recommends that pregnant women avoid any drugs, especially in the first three months, though if painkillers are needed "paracetamol is usually safe to take".
However, it is advised that pregnant women should only take the drug for the shortest amount of time possible at the lowest dose, and get advice from their midwife or GP.
Paracetamol with caffeine is not recommended as too much caffeine can result in babies having a low birth weight.
Previous studies have suggested that paracetamol can interfere with the reproductive systems of unborn children. In May 2015, experts said using paracetamol in the long term could affect the reproductive health of baby boys.
In 2014, American-led research said using paracetamol during pregnancy may raise the risk of children developing hyperactivity disorders. The results were strongest for women taking the drug for long periods of time.
Meanwhile, a study has suggested that pregnant women who take common painkillers could unwittingly be putting the fertility of their daughters at risk.
Tests on rats found that when a mother was given paracetamol or the aspirin-like drug indomethacin, her female offspring had fewer eggs than those not exposed to the medicines.
They also had smaller ovaries and 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, 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.
Professor Richard Sharpe, from the University of Edinburgh's MRC Centre for Reproductive Health, who co-led the study published in the journal Scientific Reports, 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, the scientists believe. 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.
Co-author Professor Richard Anderson, also from the University of Edinburgh, 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.