Women with a history of miscarriage or stillbirth have a higher risk of stroke in later life, a Queensland-led study has found.
University of Queensland (UQ) researchers compared data from almost 620,000 women worldwide across 11 years, finding the risk increased with multiple pregnancy losses.
The study's senior author Gita Mishra, of UQ's School of Public Health, said experiences during pregnancy acted as an early warning sign for the risk of diseases as women aged.
She said the study, published today in the British Medical Journal, identified a significant link between stroke and multiple miscarriages and "very rare events like recurrent stillbirths".
"It's an opportunity to monitor your health and make lifestyle changes that can prevent stroke. Stopping smoking, eating a healthy diet, having a moderate alcohol intake and doing regular exercise – these lifestyle measures lower the risk for everybody."
UQ PhD candidate Chen Liang led the study of women from seven countries – Australia, US, UK, Sweden, Netherlands, China and Japan – who were aged between 32 and 73 when data collection began.
More than 13,000 participants experienced a stroke, including 4,000 who died, during the study.
Ms Liang found a woman's risk of having a stroke in later life climbed with each additional miscarriage or stillbirth.
Women who had miscarried once had a 7 per cent higher risk of both fatal and non-fatal strokes compared to those who had never experienced miscarriage in pregnancy.
The risk was 12 per cent higher for a non-fatal stroke and 26 per cent higher for a deadly stroke after two miscarriages.
And after three or more miscarriages, the risk spiked by 35 per cent for a non-fatal stroke and 82 per cent for a deadly stroke.
'Our study cannot prove causation'
Putting the research into perspective, Professor Mishra said while about one in five pregnancies ended in miscarriage, less than 5 per cent of women would experience multiple miscarriages and about 1 per cent would suffer three or more miscarriages.
"In real terms what we see is – among women who had three or more miscarriages, 41 out of every 1,000 experienced a non-fatal stroke and 12 in 1,000 had a fatal stroke," Professor Mishra said.
That compares to 29 non-fatal strokes and seven deadly strokes for every 1,000 women who had never miscarried.
Professor Mishra said the risk of stroke also increased for each stillbirth a woman experienced.
She said the cause of stroke in later life among women who had experienced pregnancy loss needed more investigation.
"What we found is an association. That means our study cannot prove causation," Professor Mishra said.
"That's important because it shows that women who experience pregnancy loss, especially multiple pregnancy losses … are at an increased risk of stroke but it doesn't mean that they will definitely get the stroke."
But Professor Mishra said experiences in pregnancy could be used as a "marker" for the potential risk of developing diseases later in life, giving women the opportunity to make preventive lifestyle modifications or to discuss drug treatments.
She said women diagnosed with gestational diabetes in pregnancy were at increased risk of developing diabetes later in life and those with pre-eclampsia before giving birth were at higher risk of heart disease as they aged.
"They should be talking to their GPs," she said.
