Mean arterial pressure foretells pre-eclampsia in Asians

Mean arterial pressure (MAP) demonstrates good accuracy for estimating the risk of pre-eclampsia at term among Asian women, as shown in a study.

“Our large prospective cohort study in Asian population [indicated] that compared with angiogenic factors and uterine artery pulsatility index (UtA-PI) levels, MAP had significantly higher area under the receiver operating characteristic curves (AUCs) at 11–14, 18–22, and 28–32 weeks of gestation for prediction of pre-eclampsia, especially [that at term],” according to a team of researchers from KK Women's and Children's Hospital in Singapore.

“For the prediction of preterm pre-eclampsia, MAP and placental growth factor (PIGF) were similar. Moreover, in high-risk women, MAP, PlGF, and UtA-PI had equivalent predictive values at 11–14 weeks of gestation; in moderate-risk and low-risk women, MAP [had better predictive ability] than PlGF and UtA-PI in early pregnancy,” they added.

The study included 926 women with singleton pregnancy less than 14 weeks of gestation, among whom eight and twelve cases of preterm and term pre-eclampsia, respectively, were recorded. Those who did vs did not develop the pregnancy disorder were more likely to have obesity, chronic hypertension, previous history of pre-eclampsia, to deliver preterm, and have infants with lower birthweight.

Notably, the 20 women who developed pre-eclampsia had significantly lower levels of PlGF as well as higher levels of serum soluble fms-like tyrosine kinase 1 (sFlt-1)/PlGF ratio and MAP throughout pregnancy compared with controls without the pregnancy disorder. Based on statistical analysis, MAP indeed had better predictive ability than angiogenic factors and UtA-PI for term and preterm pre-eclampsia throughout gestation.

MAP had moderate-to-high accuracy for predicting pre-eclampsia, with AUCs of 0.86 (95 percent confidence interval [CI], 0.78–0.95), 0.87 (95 percent CI, 0.80–0.95), and 0.91 (95 percent CI, 0.85–0.98) at 11–14, 18–22, and 28–32 weeks of gestation, respectively. The corresponding AUCs for predicting term pre-eclampsia were 0.87 (95 percent CI, 0.75–0.99), 0.87 (95 percent CI, 0.76–0.98), and 0.90 (95 percent CI, 0.80–0.99). [BMJ Open 2021;11:e046161]

In the European population, the Fetal Medicine Foundation proposed a combined screening test, including maternal factors, MAP, PlGF and UtA-PI, which was found to predict 75 percent of preterm pre-eclampsia and 47 percent of term pre-eclampsia at a false-positive rate of 10 percent. However, the predictive accuracy of such an approach was lower in the Asian population, as the researchers pointed out. [Am J Obstet Gynecol 2016;214:103.e1-12; BJOG 2018;125:442-449; Am J Obstet Gynecol 2019;221:650.e1-650.e16]

“Although circulating PlGF and MAP mainly reflect placentation and maternal endothelial function, respectively, racial disparities on pathophysiology might influence the effectiveness of the predictors. As our study showed that while MAP performed better than PlGF for the prediction of pre-eclampsia and term pre-eclampsia throughout gestation … these predictors were not significantly different [with respect to preterm pre-eclampsia],” they explained.

Blood pressure [BP] measurement has been the mainstay screening and diagnostic tool in antenatal care for decades. However, the American Heart Association recommendations on BP measurement, while commonly accepted worldwide, do not specify which arm to measure and how to record the measurements. [Circulation 2005;111:697-716]

“Our experience indicates that multiple recordings in antenatal BP measurement are encouraged to achieve better accuracy of MAP,” for estimating risk of hypertensive disorders, according to the researchers.

“Although we measured BP on one arm, three continuous recordings at 1-min interval could produce an AUC of 0.86 (95 percent CI, 0.78–0.95) with 13.0 percent positive predictive value at 11–14 weeks of gestation. This performance in Asian women was better than that in European [women] where BP was measured on both arms with three recordings (AUC, 0.773, 95 percent CI, 0.768–0.778),” they added.

As such, the researchers recommended the use of appropriately sized cuff and regularly checked devices with multiple recordings in future clinical practice.