high blood pressure during pregnancy

Updated guidelines for the detection of high blood pressure can lead to improved diagnoses of pregnancy-related high blood pressure, study finds.

High blood pressure during pregnancy is associated with many risks for both the mother and the baby. High blood pressure, both chronic and pregnancy-associated (gestational), is linked to approximately 14% of maternal deaths worldwide. Infants born to mothers suffering from high blood pressure are at an increased risk of low weight at birth and cardiovascular diseases later in life.

Current guidelines define gestational hypertension as new diagnoses of blood pressure with the upper limit above 140 mm Hg (systolic blood pressure/ SBP) or the lower limit above 90 mm Hg (diastolic blood pressure/DSP). In 2017, the American College of Cardiology (ACC)/American Heart Association (AHA) revised their recommendations for diagnoses of high blood pressure in adults as values of SBP/DSP that are above 130/80 mm Hg. However, they did not make any changes in their guidelines to diagnose gestational high blood pressure.

To understand how these new guidelines from the ACC/AHA affect the detection of high blood pressure in pregnant women, researchers from Brigham and Women’s Hospital carried out a large-scale study of over 16,000 women who gave birth between September 2012 and October 2016 in Wuhan, China. They collected information from medical records of these women that included blood pressure measurements during the course of the pregnancy, blood tests for liver and kidney functions, and birth outcomes such as weight and gestational age of the newborn. The results of this large-scale study were published in the journal Circulation Research.

The researchers discovered that applying the 2017 ACC/AHA guidelines identified 25.1 percent or 4,100 women in their study group as having high blood pressure. This is in stark contrast to only 4.2 percent or 678 women diagnosed with high blood pressure using the older guidelines. As Dr. Jie Hu, lead researcher of the study, explained, “Timely, accurate diagnosis of gestational hypertension is crucial for preventing associated conditions for pregnant women like preeclampsia and postpartum chronic hypertension… Infants born to women with gestational hypertension are more susceptible to preterm birth and adverse long-term health outcomes like young adulthood cardiovascular diseases.”

The researchers suggest that adopting the 2017 ACC/AHA guidelines to diagnose high blood pressure will help better identify women at risk of gestational hypertension as well as help to monitor and mitigate the impact of increased blood pressure. “Incorporating the 2017 ACC/AHA guidelines into prenatal care practice could improve detection of high blood pressure during pregnancy and the efforts to reduce adverse maternal and neonatal outcomes in the perinatal period that are related to gestational hypertension,” said Dr.Hu.

Written by Bhavana Achary, Ph.D

Reference: Hu J, Li Y, Zhang B, Zheng T, Li J, Peng Y, Zhou A, Buka SL, Liu S, Zhang Y, Shi K, Xia W, Rexrode KM, Xu S. Impact of the 2017 ACC/AHA Guideline for High Blood Pressure on Evaluating Gestational Hypertension-Associated Risks for Newborns and Mothers. Circ Res. 2019 Jul 5;125(2):184-194

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