London, Jan 29 (IANS): Using painkillers in pregnancy may reduce fertility in subsequent generations, warns a research.

Tests conducted on rats revealed that when a mother was given painkillers during pregnancy, her female offspring had fewer eggs, smaller ovaries and smaller litters of babies than those not exposed to the drugs, the study revealed.

The findings are significant given the similarities between the reproductive systems of rats and humans, although it is difficult to directly extrapolate these results to pregnant women, the researchers noted.

"It's important to remember that this study was conducted in rats not humans, however, there are many similarities between the two reproductive systems,” said Richard Sharpe, professor at the University of Edinburgh in Britain.

In addition to affecting a mother's immediate offspring, the study also showed that the effect of such drugs were extended to the subsequent generation of rats.

The resulting females - the grand daughters of the mother given painkillers in pregnancy - also had reduced ovary size and altered reproductive function, said the researchers.

Exposed male offspring were also affected at birth - showing smaller numbers of cells that give rise to sperm in later life.

However, their reproductive function recovered to normal levels by the time they reached adulthood, the study, published in the journal Scientific Reports, said.

Pregnant women should stick with current guidelines to use painkillers at the lowest possible dose, for the shortest possible time, the researchers suggested.

Scientists tested the effects of two painkillers in pregnant rats - paracetamol and a prescription-only painkiller called indomethacin, which belongs to the same class of drugs as ibuprofen and aspirin.

Rats were given the drugs over the course of several days - four days for indomethacin or nine days for paracetamol.

"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," said co-author Richard Anderson, professor at the University of Edinburgh.