Researchers at Radboud University in the Netherlands have based their findings on an analysis of 9,000 women who had received IVF treatment to get pregnant naturally between 1985 and 1995.

They found that around one in seven did, but drinking more than four cups of coffee a day cut chances of conceiving by around 26 per cent.

In fact, they noted that 16 per cent of the women went on to conceive naturally, 45 per cent within six months of their last IVF treatment, the BBC News portal reported.

Drinking alcohol at least three times a week carried the same risk as excessive caffeine intake. But smoking more than one cigarette a day and being overweight reduced the chances of pregnancy even more, the study revealed.

The researchers estimated that a 36-year-old woman who smoked, drank too much coffee and alcohol and was overweight, and who had been through three cycles of IVF, would have a five per cent chance of a natural pregnancy.

If she was a healthy weight and did not smoke or have too much caffeine or alcohol, her chance would be 15 per cent.

According to lead researcher Dr Bea Linsten, patients should be advised how they could maximise their chances of a natural pregnancy.