Increasing numbers of "middle age pregnancies" are as great a public health problem as teenage mothers, a leading obstetrician has warned.

Research by Dr Susan Bewley, a consultant at Guy's and St Thomas' Hospital, London, has shown that more than one in five babies are born to mothers over the age of 35 and that this is putting a huge strain on NHS resources. She said ministers had to accept that the number of women falling pregnant in their late thirties and early forties was a significant health issue.

"Middle-age pregnancy is a public health problem because women en masse are moving out of the optimal age of childbearing and that brings preventable disease and stress with it," she argues in a paper to be published later this year in the Fetal and Maternal Medicine Review.

"Middle-age pregnancy has complications in the same way as teenage pregnancy," she said. "We have policies to address teenage pregnancy, but not middle-age pregnancy."