As you progress further along in pregnancy, your doctor monitors you and your baby closely. Many women with chronic hypertension have uncomplicated pregnancies and deliver at full term, either after labor is induced or spontaneously (naturally) begins.
Complications, however, are not uncommon. Chronic hypertension carries significant risk to your baby. High blood pressure can decrease placental blood flow and hinder your baby's growth and development. Placental abruption (spontaneous separation of the placenta from the uterine wall) is another serious risk.
If fetal monitoring (ultrasound) indicates growth restriction, other tests are performed to monitor your baby's response to growth restriction. If additional fetal testing, including nonstress test (monitoring fetal heart rate) and biophysical profile (specialized ultrasound evaluations), indicate inability of your baby to tolerate growth restriction, you and your doctor should consider whether your baby would benefit from early delivery with continued growth and development outside the womb. Your doctor weighs many factors in this decision, including the severity of the growth restriction and how far along you are in your pregnancy.
During this test, a Doppler instrument secured around your stomach monitors your baby's heart rate. The heart rate is then recorded with each heart beat on special paper. Your baby is considered in good health if there are multiple times when the baby's heart rate increases (accelerations) and if there are no large decreases (decelerations) in your baby's heart rate.
The biophysical profile includes a specialized ultrasound evaluation of your baby. During this test, which normally takes about 30 minutes, the amount of fluid (amniotic) around your baby is measured. Your baby is also evaluated for its ability to move and breath. A complete biophysical profile includes a nonstress test. A scores range from 0-10, with 8-10 being the highest score based upon whether or not the nonstress test is included in the final score. A score of less than 4 is concerning and may warrant delivery.
If your biophysical profile or nonstress test is non-reassuring and your doctor believes that continuing pregnancy will cause more harm than benefit to your baby, she may recommend inducing labor and delivering the baby prematurely. Medication such as oxytocin (Pitocin) may be used to stimulate contractions or to soften and shorten your cervix. Before induction of labor, your doctor may order a oxytocin challenge or contraction stress test to help predict your baby's response to labor.
The oxytocin challenge, also known as the contraction stress test, induces uterine contractions using the drug oxytocin (Pitocin). Contractions cause brief periods of impaired oxygen exchange in the placenta. If blood flow to the placenta is inadequate due to hypertension, induced contractions will augment this and the fetal heart rate should decrease. Your doctor monitors your baby's heart rate after oxytocin is administered. A stable heart rate throughout the induced contractions is a sign of fetal health. Any late decreases in heart rate are considered abnormal and your doctor may consider a cesarean section as a safer alternative to vaginal delivery.