What causes fetal demise at this stage?

Causes of Fetal Demise

Multiple factors can cause fetal demise, with the most common causes being placental abnormalities, congenital anomalies, genetic disorders, and complications specific to multiple gestations. 1

Common Causes of Fetal Demise

Placental Factors

• Placental insufficiency: A leading cause of fetal death, often associated with intrauterine growth restriction 2
• Placental abruption: Significant cause of sudden fetal death 3
• Umbilical cord abnormalities: Including cord stricture, entanglement, thrombosis, and abnormal coiling, found in approximately 10.7% of early intrauterine fetal demise cases 4
• Velamentous cord insertion: More common in twin pregnancies and associated with higher risk of fetal death 1

Genetic and Congenital Factors

• Chromosomal anomalies: Account for approximately 20% of fetal death cases 3
• Congenital malformations: Especially cardiac and central nervous system defects 3, 5
• Congenital heart defects: Associated with increased risk of fetal demise, with 47.8% of deaths related to cardiac failure 5

Multiple Gestation-Specific Causes

• Twin-to-twin transfusion syndrome (TTTS): Affects 8-12% of monochorionic diamniotic twin pregnancies 1
  • Advanced TTTS (Quintero stages III-IV) carries higher mortality risk
  • Fetal demise occurs in 24% of donors and 17% of recipients even after laser therapy 3
• Death of co-twin: In monochorionic pregnancies, death of one twin may result in demise of the co-twin in 10% of cases due to shared circulation 1
• Significant growth discordance: Discordance ≥25% associated with increased mortality 1
  • First trimester crown-rump length discrepancy >60% correlates with 100% likelihood of subsequent demise 1

Maternal Factors

• Maternal medical conditions:
  • Diabetes mellitus, especially with poor glucose control 3
  • Hypertensive disorders (preeclampsia, chronic hypertension) 3
  • Obesity 3
  • Advanced maternal age (over 35 years) 3
  • Substance use disorders, particularly opioid use 3
• Infections: Ascending infection accounts for 19% of fetal deaths, peaking at 22 weeks' gestation 2

Stage-Specific Considerations

First Trimester

• Embryonic factors: Genetic abnormalities are more common causes
• Umbilical cord abnormalities: Constriction and coiling abnormalities are frequently encountered 4
• Multiple gestations: Significant CRL discrepancy (>60%) strongly predicts subsequent demise 1

Second Trimester

• Ascending infections: Peak at around 22 weeks' gestation 2
• Nuchal translucency abnormalities: Associated with increased risk of intrauterine fetal demise 1
• TTTS: Usually manifests in mid-trimester, with severe cases evident before 20 weeks 1

Third Trimester

• Maternal vascular malperfusion: Largest category of placental abnormalities in stillbirth, with peak prevalence in early third trimester 2
• Placental insufficiency: Often associated with IUGR 3
• Post-term pregnancy: Risk increases significantly after 42 weeks 3

Risk Factors for Recurrence

• Previous fetal death increases risk in subsequent pregnancies 3
• Specific placental pathologies like chronic histiocytic intervillositis often have high recurrence rates 2
• Umbilical cord stricture may have undetermined risk of recurrence, warranting close surveillance in subsequent pregnancies 6

Evaluation After Fetal Demise

• Perinatal autopsy and placental examination: The most valuable tests for evaluation of fetal death 7
• Laboratory tests: Including Kleihauer-Betke test or flow cytometry, and blood type and antibody screen 3
• Genetic testing: Particularly important when chromosomal anomalies are suspected 3

Understanding these various causes of fetal demise is crucial for appropriate counseling, management of current pregnancy complications, and planning for subsequent pregnancies.