Your baby’s heart rate provides important information about the health and status of your baby. Several items help the healthcare team determine if your baby is tolerating the intrauterine environment.
The baseline fetal heart rate is the heart rate of your baby at rest. In most cases, the resting heart rate of the baby is between 110-160 beats per minute. Several conditions can affect the resting heart rate of the baby. For example, if mom has a fever or infection in her uterus, the baby’s resting heart rate may rise significantly. Fetal tachycardia is the term used to describe a fetal heart rate that rises and persists above 160 beats per minute. Bradycardia is the term used to describe a fetal heart rate that drops and stays below 100 beats per minute.
Temporary increases in the fetal heart rate associated with the fetal movement are known as accelerations. Just like when you exercise or move around and your heart rate increases, it is the same with the fetus. Decreases in the fetal heart rate are known as decelerations. There are several types of decelerations which are identified by their shape, timing, and duration. Variable decelerations usually are associated with umbilical cord impingement. Early decelerations occur with contractions and are associated with compression of the fetal head as it moves down the birth canal. Late decelerations begin after the peak of the contraction and last beyond the end of the contraction. Late decelerations indicate that your baby is stressed and actions should be taken to assist the baby. These actions include increasing intravenous fluid administration to the mother, putting oxygen on the mother, and changing the mother’s position. Expedited delivery may also be done if late decelerations persist.
The fetal monitor also monitors contractions. The frequency and length of contractions can be determined when an external monitor is used. Frequency, duration, strength, and resting tone can all be determined if an internal uterine monitor is placed.
Healthcare providers are trained to identify these and other patterns in the fetal heart rate and to take actions depending on the pattern in order to optimize oxygen and blood flow to the fetus to ensure fetal well-being.