Fetal Arrhythmia: Understanding the Causes and Detection Methods

Fetal arrhythmia refers to an irregular heartbeat pattern in the unborn baby. Normally, a fetus's heart rate ranges between 120 and 160 beats per minute, maintaining a relatively steady rhythm. When the heartbeat alternates between fast and slow, includes premature beats, or becomes excessively rapid, it is classified as fetal tachycardia. Conversely, if the heart rate becomes unusually slow, it may indicate a heart block. These variations are collectively referred to as fetal arrhythmias.

What Causes Fetal Arrhythmia?

Fetal arrhythmia typically arises due to abnormalities in the heart's electrical conduction system. This condition is medically termed fetal dysrhythmia and represents a pathological change in the fetal cardiac rhythm. The irregularity may be caused by structural heart defects, genetic factors, or external influences affecting the developing heart.

Common Ways Fetal Arrhythmia Is Detected

In most cases, fetal arrhythmia is first noticed either during a routine prenatal checkup when a healthcare provider listens to the fetal heart rate or when a mother uses a home fetal heart monitor. These observations often prompt further investigation to determine the type and severity of the arrhythmia.

Transient vs. Persistent Arrhythmia

It's important to distinguish between temporary and persistent forms of fetal arrhythmia. Sometimes, during an ultrasound, the pressure from the transducer may cause a brief irregularity in the fetal heartbeat. In such cases, the arrhythmia resolves on its own without requiring any medical intervention.

When Further Evaluation Is Necessary

However, if the fetus exhibits premature beats, sustained rapid heart rhythms (tachyarrhythmias), or slow heart rhythms (bradyarrhythmias), additional diagnostic tests are essential. These may include a detailed fetal echocardiogram, maternal blood tests, and continuous fetal monitoring to assess the baby's heart function and overall well-being.