Introduction
Definition and classification
Pregnancy-induced hypertension (PIH) complicates
about 6-10% of pregnancies.1 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).2
According to the Canadian Hypertension Society,
PIH refers to one of four conditions: a) pre-existing
hypertension, b) gestational hypertension and PE, c)
pre-existing hypertension plus superimposed gestational
hypertension with proteinuria and d) unclassifiable
hypertension, as is shown in Table 1.3
Epidemiology
An epidemiological study in the USA over the period
1995-2004 showed that gestational hypertension
and PE were the most commonly diagnosed hypertensive
conditions in pregnancy, whereas pre-existing
hypertension was much rarer.4 Studies from Europe
revealed a prevalence of preeclampsia at 2.3-3%.