What are the medical indications for terminating a pregnancy?

Medical Indications for Pregnancy Termination

Pregnancy termination is medically indicated for three primary categories: fetal anomalies (most common), obstetric complications threatening maternal health, and maternal medical conditions incompatible with safe pregnancy continuation.

Categories of Medical Indications

Based on recent tertiary center data, medical indications fall into distinct groups 1, 2, 3:

1. Fetal Indications (60-72% of cases)

These represent the majority of medically indicated terminations:

• Central nervous system anomalies - Most prevalent single indication (26-31% of all terminations) 1, 2
• Chromosomal abnormalities - Particularly trisomy 21 and other aneuploidies (38% in some series) 4, 2
• Multiple congenital malformations - Complex anomalies incompatible with life (17%) 4
• Severe structural defects - Cardiac, renal, skeletal anomalies detected on ultrasound

Important note: Approximately 28.9% of structural malformations have underlying genetic abnormalities when invasive testing is performed 2. The introduction of NIPT has enabled earlier diagnosis of chromosomal abnormalities, shifting terminations to earlier gestational ages 4.

2. Obstetric Indications (25-31% of cases)

These involve pregnancy complications that threaten maternal health:

• Previable premature rupture of membranes (PPROM) - Single most common obstetric indication (31.5% of all terminations) 2
• Severe preeclampsia/eclampsia at previable gestations
• Placenta accreta spectrum disorders - Particularly with complete placenta previa and prior cesarean deliveries 5
• Placental abruption with fetal demise
• Severe intrauterine infection/chorioamnionitis at previable gestations

3. Maternal Medical Indications (3-8.5% of cases)

These occur when pregnancy continuation poses unacceptable risk to maternal health 1, 3:

• Severe cardiac disease - Decompensated heart failure, pulmonary hypertension
• Malignancy requiring immediate treatment - Particularly when chemotherapy/radiation cannot be delayed
• Severe renal disease - Progressive renal failure
• Severe psychiatric illness - When pregnancy poses imminent danger
• Other life-threatening conditions - Uncontrolled diabetes with severe complications, severe autoimmune disease

Critical timing consideration: Maternal indications typically present at significantly earlier gestational ages (median 14 weeks) compared to fetal or obstetric indications 1.

Gestational Age Patterns

The timing of termination varies by indication:

• Before 24 weeks: Chromosomal abnormalities predominate and occur significantly earlier 4
• After 24 weeks: CNS malformations dominate, as many require advanced imaging for diagnosis 4
• Late diagnosis concern: Approximately 7.4% of late terminations (>22 weeks) involve anomalies that could have been diagnosed in the first trimester, highlighting the importance of early comprehensive screening 2

Safety Considerations

Contraindications to medication abortion are rare 5. The few absolute contraindications include:

• True allergy to mifepristone or misoprostol (extremely rare)
• Suspected placenta accreta spectrum without appropriate tertiary care backup 5

Relative contraindications requiring heightened monitoring:

• Two or more prior cesarean deliveries - Associated with increased uterine rupture risk (though absolute risk remains low at 0.47% with one prior cesarean) 5, 6
• Complete placenta previa - May benefit from fetal asystole induction to reduce blood loss 7
• Inherited porphyria or long-term corticosteroid therapy - Listed in mifepristone package insert but can often proceed with appropriate monitoring 5

Complications and Outcomes

Overall complication rates are low (4-12.4%) with no maternal deaths reported in recent series 4, 6. Complications increase with:

• Gestational age ≥24 weeks (complication rate 12.4% vs lower in earlier terminations) 2
• Prior uterine surgery 6
• Combined misoprostol-balloon induction methods 6

The most common complications include retained placenta, infection, need for blood transfusion, and rarely uterine rupture 6.

Clinical Approach

At periviable and post-viable gestations, inducing fetal asystole before medication abortion prevents the serious occurrence of unanticipated expulsion of a fetus with cardiorespiratory activity 7. While insufficient evidence exists to recommend routine fetal asystole induction before previable medication abortion, it becomes increasingly important as viability approaches.

Patients should ideally have treatment choice between medication and procedural abortion using shared decision-making, though this is particularly emphasized by those experiencing pregnancy complications 5.