Women on the “pill” are up to 23 per cent more likely to be on antidepressants, a study has claimed.

Scientists in Denmark examined the side-effects of hormonal contraceptives in relation to mental health. They looked at more than one million women aged 15 to 34 with no prior history of mental illness.

According to their findings, those on the combined pill were 23 per cent more likely to be prescribed an antidepressant by their doctor, most commonly in the first six months of taking the pill.

Women on progestin-only pills, a synthetic form of the progesterone hormone, were 35 per cent more likely to take antidepressants.

The risk jumped when looking at adolescent girls only. Those taking combined pills were 80 per cent more likely and those on progestin-only were twice as likely.

While the research found that women who took the pill were indeed more likely to use antidepressants, their research was unable to prove causation.

Dr Ali Kubba, a fellow of the faculty of sexual and reproductive healthcare of the Royal College of Obstetricians and Gynaecologists, said: “There is existing clinical evidence that hormonal contraception can impact some women’s moods, however, from this study there is no way of linking causation, therefore further research is needed to examine depression as a potential adverse effect of hormonal contraceptive use,” he said.

They instead suggested that women continue to use their pill as normal while more tests are carried out.

“Given the enormous size of this study, further work is needed to see if these results can be repeated in other populations, and to determine possible biological mechanisms which might underlie any possible link between the pill and depression. Until then, women should not be deterred from taking the pill,” the researchers said.