Insights from outside BJOG

Abstract

Approximately 10% of all pregnancies will be complicated by hypertension but only one-quarter of these will be diagnosed as having pre-eclampsia. The distinction is important as women with chronic or gestationally related hypertension usually present earlier and have a more benign passage through pregnancy – although they can develop superimposed preeclampsia. Much of antenatal care is devoted to the early detection of hypertensive disorders but the quest for biomarkers to predict pre-eclampsia has been largely unsuccessful. Risk scores and algorithms are promising (Sovio and Smith BJOG 2019;126:963–70) and placental growth factor testing may expedite the diagnosis of pre-eclampsia and could save admission costs (Duhig et al. BJOG 2019;126:1390–8). Early preterm pre-eclampsia is a clinical challenge and late preterm pre-eclampsia can be managed by immediate or expectant treatment in high-income countries (Chappell et al. Lancet 2019;394:1181–90). However, sudden deterioration can occur, even in optimal circumstances, and episodes of severe hypertension constitute emergencies that demand admission and an urgent decrease in blood pressure. The method of choice is intravenous antihypertensive therapy, usually hydralazine or labetalol, which are rapid acting and effective but require intensive maternal–fetal monitoring because of potential precipitous reductions in blood pressure with resultant hypoperfusion. Relatively few women worldwide have access to facilities where the safe administration of these agents is practicable, so when hypertensive crises arise in lowand middle-income countries (LMICs), oral antihypertensive drugs are given. The three most widely used are nifedipine (a calciumchannel blocker), labetalol (a combined a and b blocker) and methyldopa (a central nervous system a agonist). All are cheap, easily stored and readily available even in remote obstetric facilities. The head-to-head efficacy of these drugs was tested in a trial in India in which women presenting with a systolic blood pressure of at least 160 mmHg or a diastolic blood pressure of at least 110 mmHg were given one of these agents orally (Easterling et al. Lancet 2019;394:1011–21). Nifedipine (10 mg) or labetalol (100 mg) were given hourly with escalation if required and methyldopa was given as a 1000-mg stat dose; blood pressure control was defined as 120–150 mmHg systolic and 70–100 mmHg diastolic blood pressure. Nearly 900 women participated in the trial with a mean gestational age of 37 weeks, and four out of five of them achieved the desired blood pressure targets within 6 hours. Delivery usually followed blood pressure control, with the three drugs proving to be safe and effective despite methyldopa being restricted by its singledose constraint – a strategy that is not universally followed. These are encouraging data gathered in real-world conditions that will inspire individuals working with limited resources and prove that patients can be protected from potential hypertensive morbidity or even mortality by appropriate intervention.