Whether or not to use anti-hypertensive drugs to lower blood pressure (BP) in pregnancy remains a contentious issue, despite such drugs having been used for this purpose for almost 50 years. While this policy has broadly been adopted across Australia and New Zealand, and largely now in the United Kingdom and Europe, there is ongoing resistance to using anti-hypertensives in pregnancy in much of the United States except for treatment of severe hypertension.
This uncertainty arises from several important questions: 1) what constitutes high BP in pregnancy? 2) Can we be sure the BP is truly elevated prior to instituting anti-hypertensives? 3) Should there be differing approaches to anti-hypertensive use for women with chronic hypertension and pre-eclampsia or gestational hypertension? 4) What agents can be safely used in pregnancy? 5) Should we be tailoring anti-hypertensive use according to hemodynamic profiles?
For women with apparent essential hypertension entering pregnancy some will have ‘white-coat’ hypertension and should not receive anti-hypertensives; for the remainder a recent meta-analysis and the CHIPS trial showed that anti-hypertensive treatment reduces the likelihood of severe hypertension, particularly targeting to a diastolic BP of 85 mmHg; presumably this reduces risk of maternal stroke and may indirectly benefit the baby by prolonging pregnancy. The same arguments can be applied to treatment of pre-eclampsia or gestational hypertension but there is no clear benefit of anti-hypertensives on other outcomes for mother or baby. World-wide there is general agreement that blood pressure should be lowered acutely for BPs above 160-170/110 mmHg.
Initiating treatment is generally on a ‘one size fits all’ basis but anti-hypertensive choice could be tailored to hemodynamics.
SOMANZ has maintained a policy of ‘liberal’ anti-hypertensive use in pregnancy, which is justified; large trials are needed comparing anti-hypertensives with placebo but these may never be done. Meanwhile, the important issues are that each Unit has a uniform policy of anti-hypertensive use and that the outcomes of this are evaluated regularly.