Pregnancy-Induced hypertension

Abstract

Pregnancy-induced hypertension (PIH) complicates 6-10% of pregnancies. It is defined as systolic blood pressure (SBP) >140 mmHg and diastolic blood pressure (DBP) >90 mmHg. It is classified as mild (SBP 140-149 and DBP 90-99 mmHg), moderate (SBP 150-159 and DBP 100-109 mmHg) and severe (SBP ≥ 160 and DBP ≥ 110 mmHg). PIH refers to one of four conditions: a) pre-existing hypertension, b) gestational hypertension and preeclampsia (PE), c) pre-existing hypertension plus superimposed gestational hypertension with proteinuria and d) unclassifiable hypertension. PIH is a major cause of maternal, fetal and newborn morbidity and mortality. Women with PIH are at a greater risk of abruptio placentae, cerebrovascular events, organ failure and disseminated intravascular coagulation. Fetuses of these mothers are at greater risk of intrauterine growth retardation, prematurity and intrauterine death. Ambulatory blood pressure monitoring over a period of 24 h seems to have a role in predicting deterioration from gestational hypertension to PE. Antiplatelet drugs have moderate benefits when used for prevention of PE. Treatment of PIH depends on blood pressure levels, gestational age, presence of symptoms and associated risk factors. Non-drug management is recommended when SBP ranges between 140-149 mmHg or DBP between 90-99 mmHg. Blood pressure thresholds for drug management in pregnancy vary between different health organizations. According to 2013 ESH/ESC guidelines, antihypertensive treatment is recommended in pregnancy when blood pressure levels are ≥ 150/95 mmHg. Initiation of antihypertensive treatment at values ≥ 140/90 mmHg is recommended in women with a) gestational hypertension, with or without proteinuria, b) pre-existing hypertension with the superimposition of gestational hypertension or c) hypertension with asymptomatic organ damage or symptoms at any time during pregnancy. Methyldopa is the drug of choice in pregnancy. Atenolol and metoprolol appear to be safe and effective in late pregnancy, while labetalol has an efficacy comparable to methyldopa. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II antagonists are contraindicated in pregnancy due to their association with increased risk of fetopathy.