Hypertension is an important and serious condition in pregnancy.
Hypertension can proceed to pre eclampsia. In any event it can have very serious effects on both mother and baby.
The risks of hypertension in pregnancy may increase if the patient has had pre existing hypertensive disease or has a family history of hypertension.
A full history needs to be taken so that we might anticipate the potential risk of a patient developing hypertension in pregnancy.
Gestational hypertension develops after the 20th week of pregnancy.
Hypertensive disorders of pregnancy are associated with fetal effects:
- intrauterine growth restriction
- placental insufficiency
- placental abruption etc.
In many women pregnancy induced hypertension may progress to superimposed pre eclampsia (proteinuric hypertension).
Risks of progression to pre eclampsia may increase if the patient has:
- Antiphospholipid syndrome
- Connective tissue disorders
- Chronic renal disease
Pre eclampsia is a multisystem disorder with serious life threatening risks to maternal and fetal well-being. Its effects are widespread and can cause maternal problems such as:
- Deterioration in renal function
- Blood clotting disorders
- Risk of maternal seizures
- And of course major risks to the fetus
Pre eclampsia is a major risk in obstetrics. It requires diagnosis, stabilization and treatment, which invariably results in delivery of the baby.
Classification of hypertensive disorders in pregnancy
1a. Gestational Hypertension (developing after the 20thweek).
1b. Gestational proteinuria (developing after the 20thweek).
1c. Proteinuric Hypertension (developing after the 20thweek).
2a. Essential Hypertension (pre existing Hypertension).
2b. Chronic Renal Disease (Pre existing renal problems).
2c. Superimposed Pre eclampsia.
3. Undiagnosed (Patients who present after 20th week, diagnosed in retrospectively six weeks after pregnancy).
Severity of Hypertension
Mild Hypertension >140/90 – <155/100 mmHg
Moderate Hypertension >155/100 - <170/110 mm Hg
Severe Hypertension >170/110 mmHg
Despite these levels a significant increase in blood pressure would be any increase in systolic blood pressure >25 mmHg or a diastolic increase of >15mmHg.
If it is believed that there is a high risk of developing worsening hypertension and Pre eclampsia, it would be appropriate to commence Low dose Aspirin (LDA100 mg) and also calcium supplements (600mg). This may act to reduce or delay the development of Pre eclampsia.
Mild gestational hypertension requires monitoring to ensure there is no rapid progression. Fetal growth and well being would also need to be closely watched.
Moderate or severe hypertension would necessitate treatment with antihypertensives (Aldomet / Labetolol).
Vasodilator drugs do not necessarily vasodilate placental circulation and might potentially reduce placental perfusion. This therefore necessitates even closer supervision of fetal well-being.
If pre eclampsia develops the essence of treatment is that the patient needs to be stabilised and the fetus prepared for delivery.
More specifically the mother requires:
- Precise fluid replacement
- Use of anti hypertensive drugs
- The use of anti seizure medication (MgSo4)
If premature the baby may require:
- Steroids to stimulate lung development
- CNS prophylaxis (MgSo4 if less than 30 weeks gestation)
Women with hypertensive disease during pregnancy require fetal and maternal monitoring for signs of deterioration. The timing of delivery will be determined by the severity of the hypertension and the condition of the baby.
Although delivery will introduce the phase of recovery there are some women who will continue to deteriorate and rarely some women may have an eclamptic seizure postnatally. As a result all women will need to be monitored closely after delivery as their condition resolves. It is important to identify if any patient has any predisposing factors that could potentially lead to a recurrence of hypertensive disease or in some way adversely affect any subsequent pregnancy.