Odds of giving birth to twins expand as the family grows

THE chance of having twins rises with each baby, research has shown, busting the myth that some women are simply more fertile.

Analysis of more than 100,000 births in Europe found that the odds of giving birth to twins increases by 17 per cent with each additional child.

Although the overall odds are low – with only one to three per cent of all births leading to twins – researchers discovered that women increased their chance with each pregnancy, rather than simply releasing more eggs.

Ian Rickard, of Durham University and the first author of the report, said: “If a mother gives birth more often, it is more likely that one of these births is to twins – just like you are more likely to win if you buy more lottery tickets, or to be in a car accident if you drive a lot.”

The research found that the mothers of twins had 43 per cent more births than women who had single births.

The team of 14 scientists combined large data sets of birth outcomes from several parts of pre-industrial Europe.

Alexandre Courtiol, the principal investigator of the research, said: “Our study suggests that twinning has not been eliminated by natural selection for two reasons: first, twinning is a consequence of double ovulation, which compensates for reproductive ageing and benefits all but the youngest of mothers. Second, when the risk of early mortality of twins is not too high, twinning is associated with larger family sizes although women with twins give birth less often.”