How is fetal arrhythmia checked during pregnancy?

Fetal arrhythmia is evaluated using fetal echocardiography, M-mode, colour Doppler and pulsed Doppler to study atrial and ventricular rhythm, heart structure, function, blood flow and signs of fetal compromise.

Does every irregular fetal heartbeat need treatment?

No. Many irregular fetal beats only need monitoring. Persistent tachycardia, bradycardia, suspected heart block, hydrops or reduced fetal cardiac function require specialist assessment and coordinated pregnancy care.

When should I book a fetal heart rhythm scan?

You should book a specialist fetal heart rhythm assessment if your obstetrician notices an irregular fetal heartbeat, fast heart rate, slow heart rate, suspected fetal heart block, fetal hydrops or a heart concern on anomaly scan.

Fetal Arrhythmia in Pregnancy Nagpur

Q: What is fetal arrhythmia?

Fetal arrhythmia means that the baby's heart rhythm appears irregular, too fast, or too slow during pregnancy. Some irregular beats are temporary, but persistent rhythm abnormalities need specialist fetal echocardiography.

18–24 weeksCommon timing for detailed fetal echo

M-modeHeart rhythm timing assessment

DopplerBlood flow and rhythm mapping

GE VolusonAI-enabled fetal heart imaging

Reviewed by fetal medicine specialist

Dr. Kunda Shahane

Dr. Kunda Shahane, MBBS, MS (Obs & Gynae), FIFM, FMF (London), is Central India's first dedicated fetal medicine specialist. With nearly two decades of fetal medicine experience and 20,000+ fetuses evaluated, she provides specialist fetal heart, fetal echo, Doppler, and high-risk pregnancy assessment at Mayflower Clinic, Nagpur.

FMF London trained 20,000+ fetuses evaluated Fetal echo + Doppler expertise GE Voluson Signature Expert

Understanding the finding

What is fetal arrhythmia?

Fetal arrhythmia means that the fetal heartbeat is not following the expected regular pattern. It may be irregular, faster than expected, or slower than expected.

Some rhythm changes are temporary and may settle on their own. Others, especially persistent fast rhythm, persistent slow rhythm, suspected heart block, or rhythm change with fetal swelling, require detailed fetal echocardiography and close monitoring.

Important: If your obstetrician has written “irregular fetal heartbeat,” “fetal tachycardia,” “fetal bradycardia,” or “suspected fetal heart block,” please bring the report and previous scans for review.

Illustration: fetal heart rhythm assessment combines structure, rhythm timing and blood-flow evaluation.

Irregular beats

Extra or skipped beats are often picked up during routine scans. Many are benign, but they should be documented and followed if persistent.

Fast rhythm

A persistently fast fetal heart rhythm needs evaluation for fetal tachyarrhythmia and for signs of cardiac strain or hydrops.

Slow rhythm

A slow fetal rhythm needs careful assessment to distinguish temporary slowing from conduction problems such as suspected fetal heart block.

Common rhythm patterns

Types of fetal arrhythmia parents may hear about

The word “arrhythmia” is broad. The scan tries to identify the exact pattern, because monitoring and urgency differ from one rhythm type to another.

Premature atrial contractions

Usually described as extra beats or skipped beats. Many resolve, but fetal echo helps confirm anatomy and exclude higher-risk rhythm patterns.

Often monitored

Premature ventricular contractions

Less common than atrial ectopics and usually needs closer specialist documentation of rhythm and fetal heart function.

Needs classification

Fetal tachycardia

Persistent fast rhythm may strain the fetal heart. The scan checks heart function, valve leakage, hydrops and rhythm mechanism.

Prompt assessment

Fetal bradycardia / heart block

Persistent slow rhythm needs evaluation of atrial-ventricular relationship, maternal history and fetal cardiac function.

Specialist care

When to refer

Who should consider fetal arrhythmia assessment?

A fetal heart rhythm scan is usually advised when a routine ultrasound, Doppler, NST, or obstetric check-up suggests that the fetal heartbeat is irregular, unusually fast, unusually slow, or difficult to interpret.

It is also useful when there is a fetal heart structural concern, fetal hydrops, maternal autoimmune disease, diabetes, thyroid disorder, medication exposure, or a previous child with congenital heart disease.

Bring these if available

Previous anomaly scan or fetal echo report
Growth scan and Doppler reports
NT, NIPT, or genetic screening reports if done
Maternal blood test reports, thyroid profile, or autoimmune reports
Medication list and obstetrician referral note

Showpiece clinical table

What Dr. Kunda evaluates in fetal arrhythmia

The scan is not limited to counting the heart rate. A complete fetal heart rhythm assessment looks at rhythm, structure, function, blood flow, and fetal wellbeing together.

Area checked	What is assessed	Why it matters	Possible next step
Fetal heart rate	Average rate, rhythm pattern, persistent fast or slow rhythm	Helps classify rhythm as likely reassuring or requiring closer follow-up	Monitor Repeat scan
Atrial and ventricular timing	M-mode and Doppler timing between upper and lower heart chambers	Helps identify extra beats, tachycardia, bradycardia, conduction delay or heart block pattern	Rhythm classification
Heart structure	Four-chamber view, outflow tracts, arches, valves, septae and cardiac axis	Some rhythm concerns may be associated with structural heart disease	Detailed fetal echo
Cardiac function	Ventricular contraction, chamber size, valve leakage and cardiac strain	Persistent rhythm problems can sometimes affect fetal heart function	Urgent review if compromised
Hydrops check	Fluid around skin, abdomen, lungs or heart; placental thickness; amniotic fluid	Hydrops changes management urgency and requires coordinated care	High-risk pathway
Doppler blood flow	Umbilical artery, MCA, venous Doppler when needed and colour flow across valves	Adds information about fetal circulation and wellbeing	Surveillance plan
Pregnancy context	Gestational age, growth, amniotic fluid, maternal condition and previous reports	The same rhythm finding may have different meaning depending on the full pregnancy picture	Individualised counselling

Technology advantage

Fetal heart rhythm assessment on GE Voluson Signature Expert

Mayflower Clinic uses the GE Voluson Signature Expert for advanced fetal imaging. For fetal rhythm assessment, the machine supports systematic fetal echocardiography, M-mode rhythm analysis, colour Doppler, pulsed Doppler, STIC cardiac imaging, and AI-supported fetal heart workflow.

M-modeAssesses atrial and ventricular wall motion timing for fetal rhythm.

Colour DopplerShows blood flow across valves, chambers, great vessels, and arches.

STICCaptures 4D cardiac volumes for detailed review of fetal heart anatomy.

fetalHS AISupports stepwise fetal heart assessment and structured documentation.

Illustration: M-mode and Doppler help compare atrial and ventricular timing.

How the diagnosis is made

Why M-mode and Doppler are important

In the fetus, we cannot place ECG leads directly on the baby like after birth. Ultrasound rhythm analysis therefore uses indirect but powerful methods: M-mode movement timing and Doppler blood-flow timing.

Dr. Kunda correlates these rhythm signals with the complete fetal echo. This helps avoid mistakes such as confusing blocked extra beats with true persistent bradycardia.

Patient pathway

What happens after an irregular fetal heartbeat is found?

Confirm the rhythm pattern

The first step is to confirm whether the rhythm is truly irregular, persistently fast, persistently slow, intermittent, or related to extra beats.

Check fetal heart structure and function

A dedicated fetal echo evaluates chambers, valves, outflow tracts, arches, cardiac function, and Doppler flow.

Look for fetal compromise

The scan checks for hydrops, abnormal fluid collections, placental changes, reduced function, or associated fetal findings.

Create a monitoring or referral plan

Many cases need observation and repeat scans. Some need coordinated care with the obstetrician, fetal medicine specialist, pediatric cardiologist, neonatologist, or tertiary cardiac team.

Usually reassuring

When monitoring may be enough

Some irregular fetal beats are isolated and temporary. If fetal heart structure, function, growth, fluid, and Doppler findings are reassuring, Dr. Kunda may advise follow-up scans rather than immediate intervention.

Parents are counselled clearly about what was seen, what warning signs are being watched for, and when to return.

Needs urgent attention

When closer care is needed

Persistent fetal tachycardia, persistent bradycardia, suspected fetal heart block, reduced cardiac function, or hydrops needs more urgent specialist care and coordinated planning.

In such cases, Mayflower helps guide the next step and coordinates with the treating obstetrician and required pediatric cardiac or neonatal team.

Follow-up planning

Possible monitoring schedule after fetal rhythm assessment

The final plan depends on the rhythm pattern, gestational age, fetal heart function and the opinion of the treating obstetrician.

Same dayRhythm classification and counselling

1 weekRepeat rhythm check if frequent ectopics

2–4 weeksGrowth, Doppler and function review if needed

Third trimesterDelivery planning if rhythm persists

After birthNeonatal/pediatric cardiac review if advised

Report clarity

What your fetal arrhythmia report may include

Rhythm patternIrregular beats, tachycardia, bradycardia, suspected block, or intermittent pattern.

Heart anatomyMajor fetal cardiac views and whether structural concerns are seen.

Function and hydropsHeart pumping, valve leakage, fluid collections, and fetal wellbeing signs.

Connected services

Questions parents commonly ask

Is fetal arrhythmia always dangerous?

No. Many irregular fetal beats are temporary and do not harm the baby. However, persistent fast rhythm, slow rhythm, suspected heart block, hydrops, or reduced fetal cardiac function should be assessed by a fetal medicine specialist.

Is fetal arrhythmia detected during anomaly scan?

Sometimes. A routine anomaly scan may notice an irregular rhythm or a cardiac concern. If the rhythm needs more detail, a dedicated fetal echocardiography assessment is advised.

Which scan is best for fetal arrhythmia?

Fetal echocardiography with M-mode and Doppler is used to evaluate fetal rhythm, heart structure, function, blood flow, and signs of fetal compromise.

Can fetal arrhythmia need treatment before birth?

Some cases only need monitoring. A smaller group of persistent or serious rhythm problems may need medication planning or referral coordination through the treating obstetrician and fetal medicine team.

Should I continue with my regular obstetrician?

Yes. Dr. Kunda Shahane works as a fetal medicine specialist alongside your primary obstetrician. The goal is coordinated care, not replacement of your regular pregnancy doctor.

How soon should I book if my report says irregular fetal heartbeat?

If the report mentions persistent fast heart rate, slow heart rate, suspected heart block, hydrops, or cardiac dysfunction, book promptly. If it says isolated occasional irregular beats, your obstetrician may still advise fetal echo for documentation and reassurance.

Will the scan hurt the baby?

No. The assessment is ultrasound based. It is similar to a detailed fetal echocardiography scan and does not involve an injection or invasive procedure.

Can fetal arrhythmia be linked with fetal heart disease?

Sometimes rhythm changes occur with a structurally normal heart, and sometimes they are associated with cardiac structural or functional concerns. That is why detailed fetal echo is important.

“When parents hear the words irregular fetal heartbeat, they become anxious. Our first responsibility is to define the rhythm properly, check the fetal heart carefully, and then guide the family with clarity — whether the finding only needs observation or requires coordinated specialist care.”

— Dr. Kunda Shahane, Fetal Medicine Specialist

Book specialist assessment

Need fetal arrhythmia or irregular heartbeat evaluation?

Bring your previous scan reports, referral note, and maternal blood reports if available. Mayflower Clinic will help evaluate the fetal rhythm, explain the findings, and coordinate the next step with your obstetrician.

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Fetal Arrhythmia in Pregnancy