Women who wait less than 18 months between having children are more likely to die younger than those who have a bigger gap between siblings, research has found.

Mothers who have babies in rapid succession may be putting both their physical and emotional health at risk, experts said.

They suggested that the strain of caring for more than one young child at a time, coupled with the fact that a woman's nutritional health may be depleted by the impact of a short birth interval, may be to blame for the higher death rates.

Researchers from the Centre of Population Studies at the School of Hygiene and Tropical Medicine in London studied three sets of data from women in the UK and the US.

The largest data set covered 1 per cent of the population of England and Wales born between 1911 and 1940. Another survey from the Medical Research Council included information about 1,500 women born in 1946. The third study, from the US, tracked changes in health, employment, income and wealth for 10,000 people born between 1931 and 1941.

Analysis found that women who had less than an 18-month gap between children had a death rate after the age of 50 that was 20 per cent higher than those with a larger sibling age gap. They were also more likely to suffer long-term illnesses such as diabetes and arthritis later in life. Fathers of children born in quick succession had a slightly higher mortality rate, although the effect was not as pronounced as it was in the mothers.

Women who had five or more children, teenage mothers, and women who remained childless also had worse health outcomes.