The umbilical cord is like a lifeline for the baby when it is in the uterus. The umbilical cord supplies the baby with oxygen and nutrients. It is important to see how the umbilical cord and the fetal heart rate react during labor. Usually during a contraction, the umbilical cord is squeezed and when the contraction lets up, the umbilical cord springs back and is able to deliver oxygen to the baby. If there is a problem with the umbilical cord, the baby's heart rate will not recover as quickly after the contraction. Doctors and nurses know that if there is a problem with the baby's heart rate, it is usually because of a problem with the umbilical cord.