Pregnancy-Induced Hypertension

Pregnancy-induced hypertension (PIH) is sometimes referred to interchangeably with gestational or transient hypertension, but in practice it can be categorised into two clinical types:

• Gestational hypertension is high blood pressure that develops after 20 weeks of pregnancy without proteinuria or other signs of preeclampsia. Blood pressure usually returns to normal within six weeks of delivery.
• Transient hypertension describes a temporary rise in blood pressure during pregnancy but returns to normal within 12 weeks after delivery, without evidence of preeclampsia. 

Pregnancy-induced hypertension can present with several warning signs that expectant mothers should watch for:

• High blood pressure (>140/90 mmHg)
• Severe headaches that do not go away
• Blurred vision or seeing spots
• Pain under the ribs (upper abdominal pain)
• Sudden swelling of limbs (hands/feet) or face
• Sudden fluid retention leading to rapid weight gain and swelling
• Reduced urine output
• Thrombocytopenia (low platelet count)

Although the exact cause of PIH has not yet been identified, certain risk factors increase its likelihood:

• Women over the age of 35 years are at a moderate risk of developing PIH.
• PIH is more common in first-time mothers.
• Carrying twins or triplets raises the risk of developing PIH.
• Having PIH or preeclampsia in a previous pregnancy increases the chance of developing PIH.
• Being overweight before pregnancy contributes to higher risk.
• Pre-existing conditions, such as chronic hypertension, kidney disease, diabetes, or lupus increasethe risk of developing PIH.
• A history of PIH or preeclampsia in the family is also a key risk factor.

Hypertensive disorders of pregnancy are diagnosed through consistently high blood pressure readings (above 140/90 mmHg). As excessive weight gain during pregnancy can raise the risk of these hypertensive disorders, frequent weight monitoring is also recommended. Diagnosis of PIH is often made by exclusion. This means the patient does not develop preeclampsia (no protein in urine) and the blood pressure values return to normal by week 6 after delivery. In other words, PIH is diagnosed after ruling out other more hypertensive disorders of pregnancy, such as preeclampsia, chronic hypertension, and the superimposition of the two. One or more of the following routine diagnostic techniques are used to diagnose PIH:

• Urine tests are conducted to check for the presence of protein to rule out preeclampsia.
• Oedema assessment involves checking for swelling in both legs (bilateral leg oedema) which may indicate PID.
• Liver and kidney function tests rule out preeclampsia.
• Blood clotting tests are also performed to rule out preeclampsia.

If a diagnosis of PID is made, physicians also perform routine tests to monitor foetal health; these include:

• Ultrasound which helps monitor the baby’s development and check for complications.
• Non-stress test to observe the baby’s heart rate and ensure that they are doing well in the womb.
• Foetal movement counting, which involves keeping track of the number or frequency of foetal kicks and movements, a change in which indicates foetal stress.
• Biophysical profile is usually performed after the 28th week of pregnancy, which combines the nonstress test with ultrasound to observe the foetus.
• Doppler flow study is used to measure the flow of the foetal blood through a blood vessel.

PIH treatment focuses on managing blood pressure and preventing progression to more serious conditions such as preeclampsia. The approach depends on the severity of your condition and how far along you are in your pregnancy.

• In mild cases, doctors may recommend more rest, reducing salt intake, and frequent monitoring.
• If blood pressure is too high, doctors may prescribe antihypertensive medications to control blood pressure. If PIH progresses to preeclampsia, magnesium sulphate may be used to prevent seizures.
• In severe cases, hospitalisation may be necessary for close observation and management.
• If PIH poses risks to you or your baby, early delivery might be the best option, sometimes through labour induction or a caesarean section.

Seek medical help immediately if you experience:

• Severe or persistent headaches
• Blurred vision or vision loss
• Sudden swelling of face, hands, or feet
• Severe abdominal pain
• Reduced or absent foetal movements

Though PIH cannot be completely prevented, the following steps can help reduce the risk and support a healthier pregnancy:

• Maintaining a healthy weight is important; patients should aim for a healthy weight before pregnancy and follow the doctor’s guidance on weight gain.
• Consuming a balanced diet rich fruits, vegetables, proteins, grains, and dairy with less salt helps to control hypertension.
• Staying active through light to moderate exercise can support weight management and maintain healthy blood pressure levels.
• Attending all prenatal appointments is essential for early detection and management of PIH.
• Monitoring blood pressure at home may be advised for those at risk to keep track of any changes between appointments.

Consult an obstetrician–gynaecologist (OB-GYN). If complications arise, a maternal–foetal medicine specialist may also be involved.