The latter would include women with severe hypertension (systolic or diastolic), previous pregnancy losses and/or superimposed pre-eclampsia. High-risk chronic hypertensive patients should be seen more frequently during the antenatal period and advised that they might require hospitalisation if they develop superimposed pre-eclampsia.
Assessment and investigation A detailed history and physical examination, including current antihypertensive agents, previous surgery and previous pregnancy outcomes A screening glucose tolerance test and/or haemoglobin A1c to exclude pregestational diabetes An echocardiograph to exclude cardiac structural defects, such as left ventricular hypertrophy An electrocardiogram (ECG), particularly in those who have had chronic hypertension for >5 years, who previously had superimposed pre-eclampsia, and/or who were readmitted for severe hypertension and pulmonary oedema during a previous pregnancy Proteinuria, either by a spot urine protein:creatinine ratio or a 24-hour urine proteinuria quantitative test.
 This controversy continues,  despite the Control of Hypertension in Pregnancy Study (CHIPS) --a large randomised trial that compared tight control (<85 mmHg diastolic BP) with less-tight control (<100 mmHg systolic BP) in women with both chronic and gestational hypertension; the primary outcomes of the study showed no differences, which included superimposed pre-eclampsia, fetal growth restriction, preterm birth and abruptio placentae, although the rate of progression to severe hypertension was significantly higher in the less-tight group.
 Those with superimposed pre-eclampsia are usually delivered by the end of the 36th week of pregnancy or earlier, depending on the individual case.
Women with high-risk hypertension (severe chronic hypertension, chronic hypertension with superimposed pre-eclampsia, chronic hypertension with multiple antihypertensive agents, chronic hypertension that developed to abruptio placentae or comorbid disease) should be monitored closely for development of serious complications, such as pulmonary oedema, congestive heart failure and renal failure.
Even low-risk patients have a 10% chance of developing superimposed pre-eclampsia
and an increased chance of abruptio placentae, premature delivery and perinatal deaths compared with normotensive pregnant women.