On average, a baby in the womb has a heart rate of 110 to 160 beats per minute. This often varies by up to 25 beats per minute, according to John Hopkins Medicine. Some conditions during pregnancy or labor may affect fetal heart rate.
Uterine contractions and pushing during child birth, pain medications and anesthesia, as well as medical procedures used during delivery or pregnancy are common causes of a change in fetal heart rates. Fetal heart rate is monitored very closely throughout pregnancy and delivery to identify changes and track the well being of the baby. Both external and internal fetal heart rate monitoring are available, states John Hopkins Medicine.