Link to kidney disease highlights the need to control blood pressure in pregnancy

Now there's even more reason for pregnant women to control their blood pressure.

A recent study found that women with high blood pressure during pregnancy may face twice the risk for kidney disease within several years of giving birth. That risk climbs nearly fourfold for women who already had high blood pressure before pregnancy. And the risk is higher for Black women than for white women.

Women can help themselves with controlling high blood pressure before, during and after pregnancy. To stay within the normal range (less than 120/80 mmHG), it's important to stay physically active and eat a diet high in fruits and vegetables and low in saturated fats and sodium. They should also monitor their blood pressure regularly.

"You can't tell what your blood pressure is by how you're feeling unless it's really high or really low," said Dulaney Wilson, a research assistant professor at the Medical University of South Carolina in Charleston. She co-authored the study. "It's useful to keep track of it on a regular basis. Prevention is better than anything else, but if you can't prevent it, then catch it early."

While previous research has looked at pregnancy-related high blood pressure and kidney disease, the new study's authors said those analyses didn't include a diverse racial representation - even though Black women have higher rates of these conditions than their white peers. According to the Centers for Disease Control and Prevention, Black women also are three times more likely to die from pregnancy-related problems than white women.

It all underscores the need for good prenatal care, Wilson said. "Whoever is taking care of these women, they need to be aware that kidney disease - though the overall rate is still low - could be a serious problem."

More than 15% of women are affected by some type of pregnancy-related hypertension during their reproductive years, according to an American Heart Association scientific statement.

The conditions include preeclampsia, which can affect the kidney, liver, lungs and brain; eclampsia, when preeclampsia progresses to seizures or coma; gestational hypertension, a rise in blood pressure after 20 weeks of pregnancy; and chronic hypertension, high blood pressure before or during the first 19 weeks of pregnancy and more than 12 weeks after the baby is born. These disorders can lead to death or organ damage, including end-stage kidney disease, when the kidneys can no longer function on their own.

Researchers analyzed hospital records for 391,838 women who gave birth in South Carolina between 2004 and 2016, along with relevant birth and death certificate data. About 35% of the women were Black and 65% were white. They ranged in age from 12 to 49 when they gave birth and were followed at three, five and 14 years after delivery.

The risk of kidney disease after three years was 2.29-fold in women who developed pregnancy-related hypertension compared to women without blood pressure problems. But the risk was highest among women who also had high blood pressure before pregnancy. These women were 3.8 times as likely to develop kidney disease within three years after giving birth than their peers who had no blood pressure issues. By 14 years after delivery, it decreased to a 2.7-fold higher risk compared to women who had no blood pressure issues before or during pregnancy.

When the results were broken down by race, the risk for Black women was even greater. Black women who had both high blood pressure prior to pregnancy and pregnancy-related hypertension disorders had triple the risk for developing kidney disease within 14 years of delivery compared to Black women with no blood pressure issues, whereas white women had 1.97 times greater risk than their peers.

"This study lends further support to the idea that pregnancy can be a window into your future health," said Judette Louis, an associate professor and chair of the department of obstetrics and gynecology at the Morsani College of Medicine at the University of South Florida in Tampa.

The study, she said, also exposes more ways in which the social determinants of health - the conditions in the places people live, work and play - may be disproportionately impacting Black women.

"Some of the social determinants of health, such as a lack of access to care, may predispose them to having a delayed diagnosis and treatment for high blood pressure, which in turn can lead to problems like end-stage kidney disease," Louis said.