Chronic hypertension in pregnancy

What it is

Chronic HTN in pregnancy is hypertension present before the pregnancy, or before 20 weeks of gestational age, or persisting more than 12 weeks postpartum. There are four groups. Gestational HTN is new hypertension at or after 20 weeks with no proteinuria that normalizes within 12 weeks postpartum. Preeclampsia is hypertension with proteinuria of at least 300 mg in 24 hours or at least 1+ on dipstick, and eclampsia is preeclampsia with seizures. The fourth is chronic HTN with superimposed preeclampsia.

Before the groups, what a blood pressure normally does in pregnancy, because what is called high is built on it: blood pressure usually falls in the first trimester, particularly the diastolic, and continues to fall until 20-24 weeks; after this time the blood pressure usually increases to pre-pregnancy levels by term. So a reading at booking and the same reading at term do not carry the same meaning.

Hypertension in pregnancy is usually defined as systolic more than 140 mmHg or diastolic more than 90 mmHg, or an increase above booking readings of more than 30 mmHg systolic or more than 15 mmHg diastolic. The second half of that is the part most often missed, and it is why the booking reading is recorded at all.