Pre-eclampsia

Dr. CHAN Wan Pang

Honorary Consultant in Obstetrics & Gynaecology

Specialist in Obstetrics & Gynaecology

More than mere high blood pressure, pre-eclampsia usually only occurs after 20 weeks of pregnancy.

While the cause of pre-eclampsia remains unknown, the condition may be associated with physiological changes during pregnancy. Women who already have high blood pressure are more prone to pre-eclampsia.

According to a territory-wide audit by the Hong Kong College of Obstetricians and Gynaecologists, 2 to 3% of pregnant women suffered from mild or severe pre-eclampsia in 1999 to 2009. The symptoms of pre-eclampsia are not well-defined and vary from person to person. Most cases are diagnosed upon regular antenatal assessment.

Symptoms May Affect Both Mother and Baby if Severe

The symptoms of pre-eclampsia are myriad and have far-reaching consequences. They include:

Pre-eclampsia may be associated with small placentas and inadequate oxygenation of the baby, who may need neonatal care after birth. The mother may also suffer brain haemorrhage, liver failure, renal dysfunction and poor blood coagulation. In severe cases, even stroke and coma may occur with life-threatening consequences to both mother and baby, requiring immediate brain surgery.

Check Up Immediately if Systolic Blood Pressure is 160mmHg or Above

Due to physiological changes during pregnancy, blood vessels dilate and carry blood to the uterus. As a result, the blood pressure is usually lower than normal in the first 3 months of pregnancy.

Women may be prone to dizziness and vomiting in the early stage of pregnancy. Some of them may even faint and collapse due to irregular heartbeat, which usually returns to normal after a while. Both situations may have causes other than blood pressure.

Generally speaking, blood pressure increases as pregnancy advances. It will return to pre-pregnancy level before childbirth. The SBP and DBP of a healthy, non-pregnant woman should be no higher than 130mmHg and 80mmHg respectively. And it warrants attention if SBP reaches 140mmHg or above and DBP is 90mmHg or above during pregnancy. Admission to hospital is required if SBP stays at 160mmHg or above for a long time.   

Measure Blood Pressure Regularly

Beware of Risk Factors

Pre-eclampsia goes away only after childbirth or termination of pregnancy, and high blood pressure is one of the many symptoms of the condition. Mere control of blood pressure can only reduce the risk of complication.

In light of the serious impact of pre-eclampsia, blood pressure must be measured during antenatal check-up. Sometimes blood pressure may increase if the check-up is rushed or if one feels nervous during examination. In that case, one should take a 15-minute break before another measurement.   

Pregnant women at increased risk are also advised to measure their blood pressure at home with a clinically verified arm-type blood pressure monitor. Pregnant women are at higher risk if they had pre-eclampsia during their previous pregnancy or autoimmune diseases such as systemic lupus erythematosus, and those who have a history of high blood pressure or renal problems or a family history of high blood pressure syndromes.

While measuring blood pressure, women are advised to sit down and relax for 5 minutes before taking measurement. If the reading is high, please rest for 10 minutes and measure again.

They are advised to seek medical attention whenever in doubt. Based on one’s condition, doctor may prescribe aspirin for the period of 11^th to 14^th week of pregnancy to reduce the risk of developing pre-eclampsia in later gestation.