Hypertension during pregnancy can be a new development, or a continuation or worsening of hypertension that existed before the pregnancy. If the hypertension is diagnosed before pregnancy or during the first 20 weeks of gestation, or if the hypertension persists for six weeks after the baby is born, it is defined as chronic hypertension.
'Chronic' describes a condition that has been going on for a long time.
The reason for classifying hypertension during pregnancy is to enable you to decide what actions to take in each case. Some types (e.g. mild pre-eclampsia and gestational hypertension — see Table 19.2 below) have fewer and less severe complications for the mother and the fetus: other types (e.g. severe pre-eclampsia and eclampsia) can have fatal complications unless managed quickly.