On presentation of a pregnant woman with hypertension, the two essential elements of management are to: (1) treat any presenting emergency; and (2) classify the hypertensive disorder to plan ongoing management (Fig. 1).

Emergencies associated with hypertension in pregnancy include eclampsia, severe hypertension, stroke, hypovolaemia from placental abruption or liver rupture, and acute pulmonary oedema. These conditions need to be managed appropriately according to local guidelines.

Most women presenting with hypertension in pregnancy have no or minimal symptoms, their hypertension having been detected on routine BP measurement at prenatal clinics. History-taking should include previous medical history; previous hypertension; known cardiovascular, endocrine or kidney disease; course and outcome of previous pregnancies; family history of hypertension, kidney disease or thrombophilia; and symptoms associated with pre-eclampsia (Table 1). Physical examination, other than raised BP, may be entirely normal, but may detect clinical evidence of pre-existing hypertension. Oedema is a non-specific finding that is frequent in normal pregnancy, and, unless severe, should not be considered as evidence of pre-eclampsia (SOMANZ 2008; The Task Force on the Management of Cardiovascular Diseases during Pregnancy of the European Society of Cardiology (ESC) 2011).

Special investigations that help in classifying hypertensive orders include urine reagent strip testing for protein, or, preferably, spot urine protein:creatinine ratio. Blood investigations include haemoglobin level, platelet count, and serum creatinine and aspartate transaminase (AST). In settings with limited laboratory services, these blood tests may be omitted if the woman feels well and has a BP <160/110 mmHg, with no proteinuria and no clinical evidence of pre-eclampsia (Table 1). Assessment of uteroplacental involvement includes ultrasound fetal biometry, amniotic fluid volume assessment and umbilical artery Doppler indices. In low-resource settings, ultrasound fetal assessment can be omitted if there is no evidence of pre-eclampsia, and if uterine fundal growth is clinically assessed as normal.

The management principles of specific hypertensive disorders are discussed below, based on clinical experience and on evidence-based recommendations suggested by the World Health Organization (WHO) (Table 2).

Women with mild pre-eclampsia are usually not at immediate risk for complications. However, remission will not occur while pregnancy continues, and deterioration is likely over subsequent days and weeks. Little is gained by continuation of pregnancy at term, and therefore elective delivery (usually labour induction) is recommended from 37 weeks of gestation (Koopmans et al. 2009). Women at less than 37 weeks are best observed in hospital, with regular monitoring of BP, twice-weekly blood tests for platelet count, creatinine and AST levels, and ultrasound fetal assessment every 2 weeks. Where home BP monitoring and urine testing is feasible, women may be assessed twice weekly as outpatients. There is uncertainty about the value of antihypertensive drug treatment for mild pre-eclampsia (Abalos et al. 2007) (discussed below). There is no evidence to support bed rest in the management of pre-eclampsia (Meher et al. 2005).

The first priority in caring for pregnant women with severe pre-eclampsia is maternal stabilization, in particular lowering the BP to <160/110 mmHg. This is achieved with intravenous or short-acting oral antihypertensive drugs, followed by maintenance therapy with oral agents (discussed below). Magnesium sulphate is frequently given during stabilization, to prevent eclamptic convulsions (discussed below). For severe pre-eclampsia, hospital admission is mandatory, with close observation of maternal and fetal condition at referral level by obstetricians experienced in managing severe pre-eclampsia (Society for Maternal-Fetal Medicine and Sibai 2011). Severe pre-eclampsia places the woman and fetus at immediate threat of complications, and deterioration requiring delivery can be expected within 1–2 weeks. Once a woman is classified as having severe pre-eclampsia, she retains that classification until she delivers. Successful lowering of an elevated BP does not convert the woman to a mild category.

Early elective delivery is advised for pregnancies at term (≥37 weeks). At <37 weeks, an expectant approach is appropriate in the absence of complications. However, from 34 to 36 weeks, the risks of continuing pregnancy may be greater than the risks of prematurity for the newborn, hence the threshold for delivery is lower than at <34 weeks. If there are complications or organ system deterioration (persistent symptoms and signs, worsening kidney or liver function, eclampsia, pulmonary oedema, or deteriorating fetal condition), emergency delivery, often by caesarean section, is indicated, irrespective of gestational age (Society for Maternal-Fetal Medicine and Sibai 2011). With expectant management at <34 weeks, intramuscular betamethasone is given for 24 h before delivery to accelerate fetal lung maturity (Roberts and Dalziel 2006). In women with severe pre-eclampsia with a non-viable fetus (20–22 weeks, up to 26 weeks in low-resource settings), elective termination of pregnancy is advised in the maternal interest.

Women with severe pre-eclampsia who have thrombocytopaenia and a raised AST level, or who appear ill (nausea, vomiting, pallor) should be further tested for haemolysis (haptoglobin and serum lactate dehydrogenase levels, peripheral blood smear). Evidence of haemolysis suggests HELLP syndrome, a microangiopathic form of severe pre-eclampsia. In HELLP syndrome, delivery is indicated, irrespective of gestational age, as soon as maternal condition is stabilized (Society for Maternal-Fetal Medicine and Sibai 2011). However, the syndrome may continue to deteriorate in the first 2 days after delivery. A strong case has been made for intramuscular dexamethasone rescue treatment as specific treatment for HELLP syndrome (Martin 2013), despite findings of a Cochrane systematic review that suggested little beneficial effect (Woudstra et al. 2010).

Eclamptic convulsions are generalized tonic-clonic seizures indistinguishable from epileptic convulsions. Other causes of convulsions should always be considered, especially if the seizures are atypical. Computerized tomography or magnetic resonance imaging scanning may be recommended to exclude other causes of convulsions, or to detect cerebral damage associated with eclampsia. Immediate care for eclampsia is left lateral positioning, and oxygen by mask. Intravenous magnesium sulphate is the treatment of choice to prevent further convulsions (discussed below). Full clinical, laboratory and ultrasound assessment for pre-eclampsia, and appropriate treatment of severe hypertension, are part of initial management of eclampsia. Pregnancy should not be allowed to continue (SOMANZ 2008), and delivery is indicated within about 12 h of the first convulsion, vaginally or by caesarean section, depending on obstetric considerations. Intensive care unit admission and/or artificial ventilation may be needed for women who do not regain consciousness rapidly after convulsions, or who have co-existent complications of severe pre-eclampsia.

Women with gestational hypertension have no abnormalities other than a raised BP. Some go on to develop pre-eclampsia. Weekly attendance as outpatients is recommended with BP measurement, urine testing for protein, and, if feasible, blood testing for platelet count, creatinine and AST. Four-weekly ultrasound fetal assessment may give some reassurance. As with mild pre-eclampsia, there is uncertainty about the place and value of antihypertensive drug treatment (Abalos et al. 2007). At ≥37 weeks of gestation, there is little benefit in continuing the pregnancy, and elective delivery is advised based on evidence from a large randomized trial (Koopmans et al. 2009).