Paracetamol during pregnancy affects sex drive in male progeny: Study

Although paracetamol is usually considered safe during pregnancy, a new research from the University of Copenhagen in Denmark suggests that if you are pregnant, you should think twice before popping these pills as their use is linked to reduced sex drive and aggressive behaviour in males.

In an animal model, the use of the popular pain reliever paracetamol was found to damage the development of male behaviour, according to a paper published in the journal Reproduction.

The researchers said that the dosage administered to the mice was very close to the recommended dosage for pregnant women. 

But they cautioned that because the trials are restricted to mice, the results cannot be transferred directly to humans.

However, the researchers' certainty about the harmful effects of paracetamol means it would be improper to undertake the same trials on humans, explained David Mobjerg Kristensen, who was associated with the University of Copenhagen during the study. 

"In a trial, mice exposed to paracetamol at the foetal stage were simply unable to copulate in the same way as our control animals. Male programming had not been properly established during their foetal development and this could be seen long afterwards in their adult life. It is very worrying," Mobjerg Kristensen, now associated with the Institut de Recherche en Sante, Environnement et Travail (IRSET) in France, said.

Previous studies have shown paracetamol can inhibit the development of the male sex hormone testosterone in male foetuses, thus increasing the risk of malformation of the testicles in infants. But a reduced level of testosterone at the foetal stage is also significant for the behaviour of adult males, Mobjerg Kristensen added. 

Testosterone is the primary male sex hormone that helps develop the male body and male programming of the brain. The masculine behaviour in mice observed by the researchers involved aggressiveness towards other male mice, ability to copulate and the need for territorial marking.

"We have demonstrated that a reduced level of testosterone means that male characteristics do not develop as they should. This also affects sex drive," Mobjerg Kristensen said.

But even if paracetamol is harmful, that does not mean it should never be taken, even when pregnant, the researchers said.

"I personally think that people should think carefully before taking medicine. These days it has become so common to take paracetamol that we forget it is a medicine and all medicine has side effects. If you are ill, you should naturally take the medicine you need. After all, having a sick mother is more harmful for the foetus," Mobjerg Kristensen noted.

According to Britain's National Health Service (NHS), "paracetamol is usually safe to take" during pregnancy. 

Kristensen emphasised that pregnant women should continue to follow the guidelines given by their country's health authorities and recommends people to contact their GP if in doubt about the use of paracetamol.