High blood pressure occurs in 20 percent of pregnancies
Written by Dr. Torre Halscott, Senior Resident, OB/GYN
Elevated blood pressure is one of the more common illnesses in pregnancy, occurring in some way in up to 20 percent, or 1 out of every 5, pregnancies. This condition can lead to problems for the mother as well as the fetus while still in the uterus, and even for the baby after delivery. While most of these unfortunate outcomes are rare, they can potentially be very serious, and occasionally even life-threatening.
Some of the maternal problems that high blood pressure can lead to in pregnancy are:
- placental abruption (when the placenta separates from the uterus prematurely)
- HELLP syndrome (a condition with abnormal liver and platelet function)
- pulmonary edema (excess fluid in the lungs)
- eclampsia (seizures during pregnancy)
- kidney or liver failure, stroke, and even death
Problems for the fetus and baby include:
- preterm birth (either spontaneously or to protect the mother or baby)
- growth restriction (the fetus not gaining weight appropriately)
- low birth weight
- low amniotic fluid (the liquid around the baby inside the womb)
- brain injury and in rare cases, death
To have elevated blood pressure during pregnancy, a patient has to have a systolic reading (the larger number) of at least 140, or a diastolic pressure (the smaller number) of at least 90, two or more times, each of which is at least six hours apart from each other.
The four main types of high blood pressure in pregnancy are:Chronic hypertension (often abbreviated as (CHTN)
High blood pressure that was either diagnosed before pregnancy began, or begins earlier than the 20th week (approximately 5th month) of gestation.
Gestational hypertension (GHTN)
High blood pressure that starts after the 20th week of pregnancy, resolves within the first 12 weeks after delivery, and DOES NOT have increased protein in the urine.
Elevated blood pressure that starts after the 20th week, resolves by 12 weeks postpartum, and is accompanied by abnormal protein in the urine.
- Abnormal urine protein is often assessed by testing with a dipstick that is placed into a urine sample, though a more complete evaluation is by measuring all of the protein that is passed in a 24 hour collection (greater than 300 mg in 24 hours is abnormal).
- Preeclampsia is traditionally thought of as the condition that most commonly precedes eclampsia (seizures due to elevated blood pressure in pregnancy).
- Preeclampsia is further split into two types:
- Mild preeclampsia – when the blood pressure stays below 160 systolic (the larger number), or 110 diastolic (the smaller number), and there are no symptoms of severe disease.
- Severe preeclampsia– when blood pressure exceeds 160 systolic or 110 diastolic, and/or certain symptoms are present (listed below).
- Unrelenting headaches, persistent visual changes, difficulty breathing due to excess fluid in the lungs, severe upper abdominal pain, liver dysfunction, significantly low platelets (part of the blood that helps it clot), very decreased urine output, more than 5000 milligrams of protein in a 24 hour sample, or a fetus that is extremely small or has too little amniotic fluid around it.
- Preeclampsia is believed to be due to problems with how the placenta implants into the wall of the uterus, and how the body then reacts to this issue.
When a patient that has CHTN (by the definition above), also develops preeclampsia (diagnosed by the same urinary protein measurements as for preeclampsia on its own).
- Of all the conditions with elevated blood pressure in pregnancy, this has the highest risk of serious adverse outcomes, though they are still uncommon overall.
While these potential complications can be worrisome and even dangerous, with your doctor’s efforts along with your own, the chances of having a healthy pregnancy and childbirth are high. By all of us doing our best to diagnose and treat high blood pressure in pregnancy, we can give mothers and babies their best start possible in life together.