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.

A new IVF technique has been developed which allows fertilisation to occur in the womb rather than in the laboratory.

The technique involves putting the sperm and egg together in a small silicone capsule, which is then placed into the womb. The device, called AneVivo, is one centimetre long and one millimetre wide and contains hundreds of tiny holes that allow the fluids from the womb to surround the egg and sperm as would occur during a natural conception. After 24 hours, the capsule is removed to allow doctors to select the healthiest embryo, which is then re-implanted back into the womb.

Italy's interior minister, Angelino Alfano, has said that people who use surrogacy should be treated as sex offenders and sent to prison, in the face of Italian prime minister Matteo Renzi's attempts to grant family rights to same-sex couples.

Alfano, who made the comments while speaking to Italy's Roman Catholic Avvenire newspaper, has argued the legislation will give rise to gay couples seeking children via surrogate mothers. He was reported saying: 'We want wombs-for-rent to become a universal crime, which is punished with a jail term, just as happens for sex crimes.'

January 1 marks the official end of China's one-child policy that for 36 years has forced couples to limit their offspring to slow the country's population growth.

Last week Chinese authorities also decided to drop a plan to ban surrogate motherhood. Now aspiring parents can seek the help of Chinese women to act as surrogate mothers to gestate and give birth to their children.