The number of babies being born prematurely is increasing and over the last ten years the numbers of children surviving has risen considerably too.

Babies born before 26 weeks are more likely to survive now due to the improvements in intensive care but the proportion of those suffering serious development and health issues as they grow up remains almost the same.

Professor Kate Costeloe, who led part of the study released in the British Medical Journal, said: “I can’t pretend that we fully understand that” when commenting on why premature baby numbers are increasing but suggested it might be related to ageing mothers, obesity, and a changing ethnic mix but higher IVF rates was not related.