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Maternal-Fetal Medicine · Patient Education
Atrial Fibrillation
During Pregnancy
Understanding your heart rhythm — and what it means for you and your baby
Based on 2023 ACC/AHA/HRS Guidelines | Atlanta Perinatal Associates
Understanding the Condition
What is Atrial Fibrillation?
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Normal Rhythm
Upper and lower heart chambers beat in a coordinated, regular pattern.
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AFib Rhythm
Upper chambers beat rapidly and irregularly — out of sync with the lower chambers.
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How Common?
Affects approximately 27–166 per 100,000 pregnancies. Uncommon, but manageable.
AFib is uncommon in pregnancy. With the right care team, most patients have healthy outcomes.
Causes & Triggers
Why Does AFib Happen in Pregnancy?
🩺 Pregnancy Changes
- ▸ Blood volume increases 30–50%
- ▸ Heart rate naturally rises 10–20 bpm
- ▸ Hormones make the heart more sensitive
- ▸ Higher sympathetic (adrenaline) tone
⚠️ Additional Risk Factors
- ▸ Pre-existing heart valve disease
- ▸ Congenital heart disease
- ▸ Thyroid overactivity (hyperthyroidism)
- ▸ Electrolyte imbalances
Peak occurrence: weeks 23–30 of pregnancy (late 2nd / early 3rd trimester)
Clinical Course
AFib Across the Three Trimesters
1st Trimester
Wks 1–12
2nd Trimester
Wks 13–27
3rd Trimester
Wks 28–40
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1st Trimester
Baby's organs are forming. Lower hemodynamic stress. We focus on avoiding medications.
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2nd Trimester
Blood volume expands rapidly. AFib most likely to occur. Careful monitoring is key.
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3rd Trimester
Maximum heart load. We prepare for safe delivery and manage blood thinners carefully.
Treatment · First Trimester
1st Trimester · Weeks 1–12
First Trimester Care
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Medication Caution
We avoid starting new heart medications while your baby's organs are forming (organogenesis).
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Electric Cardioversion
A safe, controlled electrical reset of your heart rhythm — safe for you and your baby at any stage.
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Blood Thinners
Heparin injections are preferred. They do not cross the placenta and protect you from blood clots.
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Close Monitoring
Frequent visits to monitor your heart and your baby's growth and well-being.
Treatment · Second Trimester
2nd Trimester · Weeks 13–27
Second Trimester Care
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Rate Control
Metoprolol or propranolol (beta-blockers) and digoxin slow the heart rate safely.
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Rhythm Control
Flecainide or sotalol may restore normal rhythm in patients without structural heart disease.
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Anticoagulation
Blood thinners (LMWH or warfarin) are used if your stroke risk is elevated.
These medications have long safety records in pregnancy. Your team will choose the safest option for you.
Treatment · Third Trimester
3rd Trimester · Weeks 28–40
Third Trimester Care
📋 Delivery Planning
- ▸ Blood thinners stopped ~36 hours before labor
- ▸ Switch to faster-acting blood thinner near delivery
- ▸ Most patients can have a vaginal delivery
🩺 Ongoing Treatment
- ▸ Heart rate control continues as in 2nd trimester
- ▸ Frequent fetal monitoring (non-stress tests)
- ▸ Cardiology and MFM team coordinate care
Your delivery plan will be carefully prepared in advance by your entire care team.
Medications
Medications: What's Safe & What to Avoid
✅ Generally Safe
- ▸ Metoprolol / Propranolol (beta-blockers)
- ▸ Digoxin (heart rate control)
- ▸ Flecainide / Sotalol (rhythm control)
- ▸ Heparin / LMWH (blood clot prevention)
🚫 Avoid During Pregnancy
- ▸ Atenolol — linked to growth restriction
- ▸ Amiodarone — affects baby's thyroid; emergencies only
- ▸ DOACs (apixaban, rivaroxaban) — insufficient safety data
All medication decisions are individualized. Your team will always weigh benefits and risks together with you.
Effects on Your Baby
How AFib Can Affect Your Baby
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Blood Flow
Maternal tachycardia or low blood pressure can temporarily reduce blood flow to the baby (fetal hypoperfusion). Prompt treatment prevents this.
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Growth
Well-controlled AFib rarely causes growth restriction. Atenolol is the main medication linked to smaller birth weight — and we avoid it.
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Preterm Birth
Severe, uncontrolled AFib may require early delivery. Careful management greatly reduces this risk.
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Good News
AFib without structural heart disease is associated with favorable pregnancy outcomes when managed appropriately.
When to Seek Help
Call Your Doctor Immediately If You Notice:
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Rapid or Irregular Heartbeat
A sudden fluttering or pounding sensation in your chest.
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Severe Shortness of Breath
Difficulty breathing at rest or with minimal activity.
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Dizziness or Fainting
Lightheadedness, near-fainting, or loss of consciousness.
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Chest Pain or Pressure
Any tightness, pressure, or pain in your chest area.
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Sudden Leg Swelling
Rapid or asymmetric swelling in one or both legs.
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When in Doubt
Always call. We would rather hear from you than have you wait.
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Partnering for a Healthy Pregnancy
You Are Not Alone in This
AFib during pregnancy requires careful monitoring — but successful management is very common.
Your MFM and cardiology team will guide every step.
Regular Monitoring
Safe Medications
Healthy Baby
Vaginal Delivery Often Possible
AFib Often Improves After Delivery
Work closely with your team, attend all appointments, and never hesitate to call with concerns.
2023 ACC/AHA/ACCP/HRS AFib Guidelines | 2023 HRS Arrhythmia in Pregnancy Consensus Statement