Higher blood pressure prior to conception may increase the risk of miscarriage, even in women not previously diagnosed with hypertension, warn US researchers.
Their findings imply that lowering heart disease risk factors in young adulthood may also improve reproductive health, according to the study authors.
“The impact of cardiovascular risk factors starts really early in life”
The study, published in the American Heart Association’s journal Hypertension, involved women who had already experienced at least one pregnancy loss and were trying again.
Its authors said it was the first research to look at preconception blood pressure and reproductive outcomes in healthy women not diagnosed with high blood pressure or heart disease.
The researchers studied 1,228 women, who had already experienced one to two pregnancy losses and were currently trying to become pregnant.
The women, who had an average age of 28.7 years, were part of a clinical trial to determine whether taking low-dose aspirin might reduce the risk of miscarriage.
During the study, women had their blood pressure measured when they were trying to become pregnant and again during early pregnancy.
Average blood pressure prior to pregnancy was 111.6/72.5mmHg. Of the 797 women who conceived within six months, 24% experienced a pregnancy loss.
Researchers also found that every 10-point increase in diastolic blood pressure was associated with an 18% increased risk of pregnancy loss.
In addition, every 10-point increase in mean arterial pressure – an average of the diastolic and systolic numbers – was associated with a 17% increased risk of pregnancy loss.
The findings were similar for preconception and early-pregnancy blood pressure, said the researchers from the US National Institute for Child Health and Human Development in Maryland.
Lead study author Dr Carrie Nobles said: “Elevated blood pressure among young adults is associated with a higher risk of heart disease later in life, and this study suggests it may also have an effect on reproductive health.”
“Preconception is a previously unrecognised critical window for intervention”
Senior study author Dr Enrique Schisterman said: “The impact of cardiovascular risk factors starts really early in life.”
He suggested clinicians treating women of reproductive age should “pay attention to slightly elevated blood pressure because it may have other not-well-recognised effects”.
He added: “Preconception is a previously unrecognised critical window for intervention such as lifestyle changes that can help prevent later heart disease and may also improve reproductive health.”
The researchers noted that whether or not women had been randomly assigned to take low-dose aspirin as part of the trial made no difference in the impact of blood pressure on pregnancy loss.
In addition, because the study was conducted in women who already had experienced a miscarriage, they said it was unclear whether the results could be generalised to all young women.