Fetal Monitoring 1957 – Medical Monitoring of the Baby in the Womb

Childbirth is among the most stressful situations a human can endure, yet newborns are remarkably well adapted to overcoming this major challenge. Nevertheless, signs of fetal distress must be watched for. Before the invention of electronic fetal monitoring, doctors found it difficult to assess a fetus's health beyond listening to the fetal heart with a special stethoscope. For example, the fetal heartbeat might not be audible during maternal uterine contractions, when fetal distress could occur.

In 1957, American physician Orvan Hess and his colleague Edward Hon invented a fetal heart monitor. It was a 2-meter-tall machine that could continuously monitor electrical heart signals received from the fetus. Today, cardiotocography (CTG) refers to the simultaneous recording of the fetal heartbeat and uterine contractions during pregnancy. External measurements use an ultrasound sensor to detect the movements of the fetal heart. A pressure-sensitive device simultaneously measures tension in the uterus, providing an indirect indication of pressure inside the uterus.

CTG continuously monitors the frequency, duration, and intensity of uterine contractions. The normal fetal heart rate is between 110 and 160 beats per minute. Fetal needs may be compromised if the mother smokes or has conditions such as abnormal placental placement, asthma, diabetes, pneumonia, abnormal blood pressure, or anemia. Fetal monitoring can be used to anticipate impending fetal hypoxia (low oxygen), allowing steps to improve uteroplacental blood circulation and prevent harm to the newborn.

Historical Figures Mentioned in This Article: Orvan Walter Hess (1906–2002), Edward Hon (1917–2001)

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