What Causes High Blood Pressure in Pregnancy?


High blood pressure during pregnancy typically begins near the middle or end of the second trimester 13. If high blood pressure wasn't an issue before pregnancy, it is often caused by protein in the mother's urine from kidney problems that developed during pregnancy 13. Most women with slightly elevated blood pressure are able to carry their babies to term with a natural delivery, but this condition needs to be monitored by a doctor. For women who have never had high blood pressure before, this condition is called gestational hypertension 1.

Typical Pregnancy

Most women experience a drop in blood pressure sometime during the second trimester. Occasionally, a slight increase will occur, and this isn't a problem as long as it is monitored by the doctor.


Women with high blood pressure before pregnancy often see their condition worsen while carrying the baby 13. This can damage the mother's organs, particularly the kidneys. A lower birth weight for the baby is often the result. Preeclampsia, also known as toxemia during pregnancy, can be life threatening if the condition becomes severe 23. Low birth weight and premature birth can result.

Worst-Case Scenario

Severe preeclampsia can cause seizures; this is when the condition becomes eclampsia, which is one of the leading causes of death of the mother and baby 2.

Risks of High Blood Pressure During Pregnancy

High blood pressure decreases the baby's supply of oxygen and nutrients carried by the blood and delivered through the placenta 13. This can cause the placenta to pull away from the uterus. When this happens, the baby might need to be delivered early to prevent further complications. Women who have gestational hypertension are more likely to have heart disease later in life.

Signs of Preeclampsia

Signs of preeclampsia include headaches, blurred vision, abdominal pain and unexplained sudden weight gain (more than five pounds per week) 2.

Prevention of High Blood Pressure

Before getting pregnant, check your blood pressure and get it to a healthy level 1. Limit salt intake, increase physical activity and maintain a healthy weight. Before taking any medications, discuss them with your doctor. If you are already on high blood pressure medication before the pregnancy, talk to your doctor and find out if the dosage needs to be adjusted 13.