DALLAS – Previously normotensive women who develop a hypertensive disorder during pregnancy are at more than double the risk of being diagnosed with prehypertension or hypertension within the first year after delivery, according to a large California study.
"Early postpartum screening and improved follow-up of women with hypertensive disorders first identified during pregnancy may be necessary to identify those at risk for future hypertension or prehypertension," Mary Helen Black, Ph.D., concluded in presenting the results of her population-based study at the American Heart Association scientific sessions.
The study was a retrospective review of the comprehensive electronic health records of 5,960 women who received their prenatal care and subsequently delivered a live singleton neonate at 20 weeks’ gestation or more at a single Kaiser Permanente Southern California medical center during 2006-2010. All of these women were specifically identified as being normotensive prior to their pregnancy and 6% of them developed a hypertensive disorder in pregnancy; 215 of the 358 affected women had preeclampsia or eclampsia.
Dr. Mary Helen Black
During the first year after delivery, 63 women, or 1.1% of the total study population, developed frank hypertension. Another 902, or 15%, developed prehypertension during that first year. Prehypertension was defined as a modestly elevated blood pressure of at least 120/80 mm Hg on two consecutive ambulatory visits.
After adjustment for potential confounders including age, race, parity, prepregnancy body mass index, and smoking status, previously normotensive women with hypertension in pregnancy had an adjusted 2.4-fold increased risk of developing hypertension or prehypertension in the year after delivery, compared with women without any hypertensive disorder in pregnancy. Women who developed preeclampsia or eclampsia had a 2.5-fold increased risk, according to Dr. Black, a research scientist at Kaiser Permanente Southern California in Pasadena.
Protocols exist for monitoring and treatment of pregnant women identified as having chronic hypertension prior to pregnancy. However, the new Kaiser study is one of the first to look at the downstream impact of hypertensive disorders in pregnancy arising among women with no preexisting indication of hypertension. The plan is to follow these women further to learn how their clinical outcomes progress. Long-term Scandinavian registry studies have linked hypertensive disorders in pregnancy to increased risk of eventual type 2 diabetes, hypertension, and cardiovascular disease.
Dr. Black and her coinvestigators are planning a postpartum intervention study aimed at preventing onset of type 2 diabetes and cardiovascular disease in previously normotensive women with hypertensive disorders in pregnancy. Serious consideration is being given to intervening with the DASH diet and other nonpharmacologic interventions, she said.
While women with chronic hypertension prior to pregnancy are known to be at increased risk for development of preeclampsia and other hypertensive disorders of pregnancy as well as for gestational diabetes mellitus, the situation regarding women with prepregnancy prehypertension has been less clear. Dr. Black and coworkers shed new light on this issue in a separate study presented at the AHA meeting. She reported that women with prepregnancy prehypertension are also at increased risk for these pregnancy complications.
This study involved 2,156 Kaiser Permanente patients with prepregnancy prehypertension and 5,646 who were normotensive. A total of 8.4% of the women developed a hypertensive disorder during pregnancy, including 373 with preeclampsia/eclampsia. In addition, 1,877 women developed gestational diabetes mellitus.
Women with prehypertension prior to pregnancy were an adjusted 2.7-fold more likely to develop a hypertensive disorder in pregnancy, 2.2-fold more likely to have preeclampsia/eclampsia, and 1.2-fold more likely to develop gestational diabetes than women who were normotensive before pregnancy.
The risk of preeclampsia/eclampsia among women with prepregnancy prehypertension was significantly greater if they were at least 30 years old than if they were younger.
Both studies were funded by Kaiser Permanente. Dr. Black is an employee of the company.