30th June 2023

Hypertension in pregnancy

As with diabetes, hypertensive disorders in pregnancy include new-onset hypertension and pre-existing hypertension which is recognised for the first time in pregnancy.

Hypertension in pregnancy is diagnosed at 140/90mmHg, and therapy to reduce this to 135/85mmHg should be offered if it is persistently elevated. The first line treatment is labetalol, with nifedipine second line, and methyldopa third line. Outpatient management includes BP monitoring, urine dipstick for proteinuria 1-2 times a week, and weekly bloods to screen for pre-eclampsia. Growth scans are also offered as both hypertension and beta blockers are linked to babies who are small for gestational age.

Women with BP >160/110mmHg should be admitted for initial management. This may be with oral or IV labetalol, oral nifedipine or IV hydralazine.

Post-delivery, women should continue their antihypertensive therapy; this should be reduced if BP <130/80. The exception to this is with methyldopa; this needs to be changed or stopped within two days of delivery due to the link with postnatal depression. These women should be reviewed at 2/52 postpartum and 6/52 postpartum by their GP.

Pre-eclampsia

Pre-eclampsia is a multi-system disorder with a wide variety of presentations and disease progression; the underlying cause is thought to be related to vascular endothelial dysfunction and abnormal placentation.

Risk factors for developing pre-eclampsia include hypertension in previous pregnancy, CKD, autoimmune disease, i.e. SLE or APLS, pre-existing diabetes and chronic hypertension. Women with these risk factors, as well as those with two or more moderate risk factors, should be offered 75-150mg aspirin daily from 12/40 until birth. Moderate risk factors are 1st pregnancy, age >40, pregnancy interval >10 years, BMI >35, family history of pre-eclampsia and multiple pregnancy.

The presence of new or worsening hypertension after 20/40, with either proteinuria (PCR>30) or evidence of maternal organ dysfunction or utero-placental dysfunction, makes the diagnosis of pre-eclampsia.

The management is dependent on the gestation and severity of pre-eclampsia, however, BP control and monitoring for severe pre-eclampsia form the mainstay of treatment preterm until the benefits of delivery outweigh the risks associated with preterm delivery. Diagnosis from 37/40 should lead to the offer of delivery within 24-48 hours.

Severe pre-eclampsia, HELLP and eclampsia

Severe pre-eclampsia includes BP >160/110 with significant proteinuria and/or maternal organ dysfunction. The symptoms include ongoing or recurrent severe headaches, visual scotoma, nausea or vomiting, epigastric pain and oliguria. Signs include hyperreflexia or >2 beats of clonus, liver tenderness and oedema.

HELLP (Haemolysis, Elevated Liver enzymes and Low Platelets) is diagnosed when ALT is >70 IU/L or rising, with platelets <150 x10⁹/L and falling. Immediate delivery is indicated with antihypertensive therapy and IV magnesium sulphate (bolus 4g then 1g/hr).

Eclampsia is diagnosed when a tonic-clonic seizure occurs in association with possible pre-eclampsia. Hyperreflexia may be the only preceding symptom. Most eclamptic seizures are self-limiting; mainstays of management include reducing the risk of recurrence with IV magnesium sulphate, controlling the BP and delivery of the baby if the seizure is pre-delivery.