Fetal Arrhythmias
During Pregnancy

A guide for expectant parents

OpenMFM.org · Atlanta Perinatal Associates · Maternal-Fetal Medicine

How Common Is This?

1–2%

of all pregnancies

~86%

are benign extra beats

What Is a Fetal Arrhythmia?

An arrhythmia is a change in the rate or regularity of your baby's heartbeat. It can mean the heart beats too fast, too slow, or with extra beats.

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Ectopy

Extra Beats

Most common. Usually harmless extra beats from the upper chambers.

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Tachycardia

Too Fast

Heart rate persistently above 160 bpm. Requires closer monitoring.

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Bradycardia

Too Slow

Heart rate persistently below 110 bpm. Less common; carefully evaluated.

The Normal Heart Rate Range

A healthy fetal heart rate falls between 110 and 160 beats per minute. We check this at every ultrasound appointment.

60 bpm200 bpm

Too Slow (<110) Normal (110–160 bpm) Too Fast (>160)

Bradycardia

Normal Range

Tachycardia

Why Does It Matter?

A baby's heart is still developing. Extreme heart rates — very fast or very slow — can make it harder for the heart to pump blood effectively.

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Our Concern

Cardiac Output

Sustained abnormal rates can reduce blood flow to the baby's organs.

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Rare Complication

Fetal Hydrops

Fluid buildup in the baby — rare, but the reason we monitor carefully.

What Causes It?

Most arrhythmias occur in structurally normal hearts with no identifiable cause. Some have specific associations we evaluate for.

1

Premature beats (ectopy): Usually no underlying cause. Often disappear before or after birth.
2

Fast rhythms (SVT / Atrial Flutter): Typically no structural heart problem. Responds well to treatment.
3

Slow rhythms (Heart Block): May be linked to maternal antibodies (anti-Ro/SSA, anti-La/SSB) or a heart structural difference. We test for these.

How We Evaluate Your Baby

All tests are safe and non-invasive for you and your baby.

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Primary Tool

Fetal Echo

Detailed ultrasound of the baby's heart — structure and rhythm assessed together.

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Advanced Option

Fetal MCG

Records magnetic signals from the fetal heart — like a prenatal ECG. No radiation.

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Maternal Labs

Blood Tests

Screening for antibodies that may affect the baby's heart rhythm.

Treatment Options

Treatment depends on the type of arrhythmia and how your baby is doing.

Approach	When Used	What It Involves
Observation	Benign extra beats; no symptoms	Regular ultrasounds; no medication needed
Medication	Persistent fast rhythm (SVT, Atrial Flutter)	You take medication; it crosses the placenta to treat your baby
Steroids	Early-stage heart block with maternal antibodies	Fluorinated corticosteroids to reduce inflammation
Delivery Planning	Treatment not working; worsening condition	Carefully timed delivery with neonatal team ready

About the Medications

When medication is needed, you take it — it safely crosses the placenta to reach your baby. We monitor you closely throughout.

1

We perform a baseline ECG on you before starting any medication.
2

Regular follow-up ECGs and lab checks ensure the medication is safe for you.
3

Fetal echocardiograms confirm the medication is working for your baby.

Your Care Team

You are never alone in this. A specialized team works together on your behalf.

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Your Doctor

Obstetrician

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High-Risk Specialist

Maternal-Fetal Medicine

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Heart Specialist

Pediatric Cardiologist

All three specialists communicate regularly and coordinate your care plan.

Monitoring Schedule

How often we see you depends on the type and severity of the arrhythmia.

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Benign Ectopy

Every 4–6 Weeks

Routine ultrasound monitoring; no medication required.

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Active Arrhythmia

Weekly

Fetal echocardiogram to check rhythm and look for fluid changes.

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On Medication

Bi-Weekly

Echo plus maternal ECG and lab monitoring while on treatment.

Delivery & After Birth

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Pregnancy

Monitoring & treatment as needed. Goal: reach full term.

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Delivery

Most deliver at term. Neonatal team is present and prepared.

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Newborn

Postnatal ECG performed. Pediatric cardiologist follows up.

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Follow-Up

Most arrhythmias resolve. Continued monitoring as needed.

What You Can Do

1

Attend all appointments. Regular ultrasounds are your most important tool.
2

Take medications as prescribed. Do not stop without talking to your doctor first.
3

Report changes. Call us if you notice decreased fetal movement or feel unwell.
4

Ask questions. No question is too small. We are your partners in this journey.

We Are In This Together

A fetal arrhythmia diagnosis can feel overwhelming. Our team is here to guide you, answer your questions, and ensure the safest possible outcome for you and your baby.