Decelerations
Decelerations refer to temporary drops observed in the fetal heart rate. There exist three fundamental types of decelerations which include early decelerations, late decelerations, and variable decelerations. Typically, early decelerations are considered normal and not a cause for concern. On the other hand, late and variable decelerations may sometimes signify that the baby is not performing well.
Early Decelerations Fetal Heart Rate
Early decelerations occur before the peak of a contraction, often when a baby’s head is compressed during later stages of labor or during early labor for premature or breech babies. Although early decelerations can be uncomfortable, they are generally not harmful.
Late Decelerations Fetal Heart Rate
Late decelerations are dips in fetal heart rate that start at the peak of a contraction or after the contraction is over. These dips are usually shallow and mirror the shape of the contraction that causes them. Late decelerations may not be a problem if the baby’s heart rate also shows accelerations and a quick return to normal.
However, if late decelerations occur together with a fast heart rate and very little variability, this may indicate that the fetus is not getting enough oxygen. In such cases, contractions may be harming the baby by depriving it of oxygen. In such scenarios, a doctor may choose to perform an urgent or emergent cesarean section if the fetus is in danger.
Variable Decelerations Fetal Heart Rate
Variable decelerations are dips in the fetal heart rate that occur irregularly and look more dramatic than late decelerations. These decelerations happen when the umbilical cord is compressed, which is a common occurrence during most labors. As the baby depends on steady blood flow through the umbilical cord for oxygen and other nutrients, repetitive variable decelerations can be a sign of reduced blood flow and can be harmful to the baby.
Doctors determine whether variable decelerations are a problem by monitoring other factors from heart rate monitors and how close the baby is to being born. In cases of severe variable decelerations early in labor, doctors may recommend a cesarean section. However, if variable decelerations occur before delivery and are accompanied by accelerations, it is considered a normal occurrence.
What to Expect
The procedure for monitoring fetal heart rate is painless, but internal monitoring can be uncomfortable. There are very few risks associated with this procedure, so it’s routinely done on all women in labor and delivery. Talk to your doctor, midwife, or labor nurse if you have questions about your baby’s heart rate during labor.
How to Read Strips
Reading the strips for fetal heart rate monitoring requires training. It is important to remember that a variety of factors, not just heart rate, can determine how well your baby is doing.