The “political” enthusiasm for women to have more babies will not come without a downside. Complications such as pre-eclampsia — a major cause of premature delivery — are likely to become more prevalent as increasing numbers of women become pregnant when they are older or obese, and may affect up to 5% of these women. The reason why pre-eclampsia develops is an enigma. Although there have been no recent major advances in the clinical treatment of this diverse disorder, maternal and fetal outcomes in Australia and New Zealand are good.1 The big risk now is that obstetricians, physicians, general practitioners and midwives will become complacent about the management of these high-risk pregnancies.

The institution of standardised surveillance guidelines for Canadian women with pre-eclampsia has been associated with a reduction in adverse maternal outcomes (from 5.1% to 0.7%), but not perinatal outcomes.2 For this reason, the updated Australian and New Zealand Guidelines for the management of hypertensive disorders of pregnancy,3 assuming they are adopted, should improve outcomes for women with hypertension in pregnancy. These guidelines, which were produced in 2008 by the Society of Obstetric Medicine of Australia and New Zealand (SOMANZ), highlight key aspects of these complex disorders. First, the traditional definition of pre-eclampsia — as only hypertension with proteinuria — fails to identify women who are at high risk by having other organ involvement (eg, hepatic, haematological or cerebral disease) without proteinuria.4 Second, a spot urine protein : creatinine ratio can be used to detect significant proteinuria, and 24-hourly urine collections are no longer necessary in routine clinical management.5 Third, although all women with pre-eclampsia should initially be admitted to hospital, many hospitals now have a day assessment unit where some patients with pre-eclampsia can be managed as outpatients — providing their initial assessment was as an inpatient.

The treatment of these disorders is “supportive”, and does not ameliorate placental abnormalities or alter the pathophysiological sequelae of pre-eclampsia. Treatment of hypertension in pregnancy does not cure pre-eclampsia; it is intended to prevent cerebral haemorrhage and eclampsia (seizures), and may delay proteinuria.6 SOMANZ recommends antihypertensive treatment be commenced promptly in all pregnant women with a systolic blood pressure of 170 mmHg or higher, or a diastolic blood pressure of 110 mmHg or higher. Several rapidly acting agents are suitable for controlling severe hypertension, including oral nifedipine, intravenous labetalol and intravenous hydralazine.7

Treatment of mild to moderate hypertension in the systolic blood pressure range of 140–160 mmHg or diastolic blood pressure range of 90–100 mmHg is more controversial; however, most hospitals in Australia and New Zealand do implement treatment at these levels. At higher levels, treatment is mandatory, and several drug treatments are safe and efficacious: methyldopa, labetalol and oxprenolol are first-line options, and hydralazine, nifedipine and prazosin are second-line options. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are contraindicated in pregnancy.

The drug of choice for the prevention and treatment of eclampsia is intravenous magnesium sulfate. However, eclampsia complicates only one in 200–300 cases of pre-eclampsia in Australia, and the case for its routine administration in women with pre-eclampsia in countries with low maternal and perinatal mortality rates is not compelling. SOMANZ recommends magnesium prophylaxis only for women considered at high risk of seizures.

Some preterm cases are managed expectantly in units that treat patients at high risk, but delivery remains the definitive management. Many women with pre-eclampsia deteriorate for a few days after delivery, and they require close monitoring during this phase. When there is intense pressure to discharge patients quickly, this is an important point to remember.

Women want to know their risk of developing recurrent pre-eclampsia or gestational hypertension, which is about 15% for each after pre-eclampsia in the index pregnancy.8 These rates are probably higher after early-onset pre-eclampsia. Low-dose aspirin and calcium supplementation have both been shown to reduce the risk of pre-eclampsia, and should be used in women at high risk of pre-eclampsia, such as those with a history of early-onset pre-eclampsia.

It is apparent that women with either pre-eclampsia or gestational hypertension are at increased risk of cardiovascular morbidity in subsequent years, including hypertension, stroke, coronary heart disease, venous thromboembolism and overall mortality.9 These associations could reflect a common cause for pre-eclampsia and cardiovascular disease, or an effect of pre-eclampsia on vascular disease development, or both. A similar risk for later end-stage renal failure has been reported recently, however only 0.08% of women were affected.10 From a practical point of view, it is reasonable to counsel patients who develop hypertension in pregnancy that they will benefit from avoiding smoking, maintaining a healthy bodyweight, exercising regularly and eating a healthy diet. It is recommended that all women with previous pre-eclampsia or hypertension in pregnancy have an annual blood pressure check and regular (at least 5-yearly) assessment of other cardiovascular risk factors, including serum lipids and blood glucose. In other words, hypertension in pregnancy has become a lifelong disorder. Risks and practice recommendations for women with hypertensive disorders of pregnancy are summarised in the Box.