Women who delay starting a family are more likely to have a stroke or heart attack later in life, a major study has concluded.

Scientists found women who give birth after the age of 40 are two-thirds more likely to die of cardiovascular disease when compared to those who become mothers earlier.

Experts said their findings, based on a study of 72,000 women, showed the consequences of late motherhood could last for years.

The number of older mothers has soared in recent decades, as more women concentrate on their career and start families later.

The proportion of women over 40 giving birth in England and Wales has trebled in the last 30 years, from 4.9 per 1,000 in 1984 to 14.7 per 1,000 in 2014.

The Office for National Statistics said last year this was because women are ‘increasingly delaying childbearing to later in life’.

Doctors have repeatedly urged women to heed warnings about putting off a family, pointing out fertility drops significantly from the late-30s, and that IVF may be required if natural conception fails.

The risk of complications during pregnancy increases with later motherhood, they warn, and babies born to older women have a higher chance of birth defects.

But the new study, conducted at the University of Minnesota, reveals older motherhood also has long-term implications for a women’s health that may last for years.

The team looked at data from 72,221 women who were tracked for 12 years in old age as part of the US Women’s Health Initiative Study.

Researchers compared the health of the 5 per cent of the group who had given birth after the age of 40, to those who had children at an earlier age.

According to the results, presented yesterday at the American Stroke Association Meeting in Los Angeles, those mothers who had given birth after the age of 40 were 70 per cent more likely to die of cardiovascular disease later in life.

They were also twice as likely to have a haemorrhagic stroke - the kind caused by a brain bleed - and a fifth more likely to have a heart attack.

Their risk of an ischaemic stroke - the type caused by a blood clot - increased by 60 per cent, the scientists found.

Despite the large increase in relative risk linked to late motherhood, the absolute chance of health problems remained small.

Deaths from cardiovascular disease, for example, increased from 2.3 per cent among women who gave birth young to 3.9 per cent among those who had been older mothers.

Heart attack risk increased from 2.5 per cent to 3 per cent, ischemic stroke risk from 2.4 per cent to 3.8 per cent, and haemorrhagic stroke risk from 0.5 per cent to 1 per cent.

Lead researcher Professor Adnan Qureshi said: ‘We already knew older women were more likely than younger women to experience health problems during their pregnancy.

‘Now, we know the consequences of that later pregnancy stretch years into the future.’

The team said most of the increased risk was because older women are more likely to have high blood pressure, diabetes or high cholesterol when they become pregnant - which increases the risk of problems down the line.

Professor Qureshi added: ‘Women with a late pregnancy need to be aware of their increased risk and take steps to improve their cardiovascular health.

‘Their doctors need to remain vigilant years later in monitoring these women’s risk factors through physical examination and, perhaps more tests and earlier interventions to prevent stroke and other cardiovascular events.’

Women who never have children are also at increased risk of health problems. 

Figures published yesterday by Cancer Research UK showed that rates of womb cancer have increased by a quarter in the last decade. 

The risk of the illness is a third higher in women who have never had children, because they are more exposed to the hormone oestrogen which may trigger tumour growth.