High blood pressure during pregnancy — even once or twice during routine medical care — can signal substantially higher risks of heart and kidney disease and diabetes, according to new research in the American Heart Association journal Circulation.

“All of the later life risks were similar in pregnant women who could otherwise be considered low-risk — those who were young, normal weight, non-smokers, with no diabetes during pregnancy,” said Tuija Männistö, M.D., Ph.D., lead author of the study and a postdoctoral fellow at the National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development in Rockville, Md. 

Studies have shown higher heart and kidney disease risk in women with preeclampsia, a serious pregnancy-related disease marked with high blood pressure and measurable protein in the urine.

In the new study, researchers looked at less serious forms of high blood pressure that are much more common in pregnant women. For 40 years, they followed Finnish women who had babies in 1966. They calculated the risk of heart or kidney disease or diabetes in later life among women with high blood pressure during pregnancy, comparing them to women with normal blood pressure during pregnancy.

They found: 

• One-third of the women had at least one high blood pressure measurement during pregnancy. 
• Women who had any high blood pressure during pregnancy had 14 percent to over 100 percent higher risk of cardiovascular diseases later in life, compared to women with normal blood pressure during pregnancy. 
• Women who had any high blood pressure during pregnancy were 2 to 5 times more likely to die from heart attacks than women with normal blood pressure during pregnancy. 
• Women who had high blood pressure during pregnancy and healthy blood pressure levels after pregnancy had a 1.6- to 2.5-fold higher risk of having high blood pressure requiring medication or hospitalization later in life. 
• Women who had high blood pressure during pregnancy had a 1.4- to 2.2-fold higher risk of having diabetes in later life. 
• Women who had transient high blood pressure with and without measurable protein in the urine had a 1.9- to 2.8-fold higher risk of kidney disease in later life, compared to women with normal blood pressure during pregnancy. Transient high blood pressure is temporary high blood pressure that later returns to normal.

“According to our findings, women who have had high blood pressure during pregnancy or who are diagnosed with high blood pressure in pregnancy for the first time might benefit from comprehensive heart disease risk factor checks by their physicians, to decrease their long-term risk of heart diseases,” Männistö said. 

Future research should estimate how lifestyle changes during pregnancy, such as diet, affect the risk of developing high blood pressure during pregnancy, Männistö said. Studies also should focus on how lifestyle changes and clinical follow-up after pregnancy could change these women’s long-term health. 

Because the study was limited to non-Hispanic Caucasian Finnish women, researchers said they aren’t sure if results would be the same for other racial and ethnic groups.