What increases the risk of another fetal anomaly after a previous one?

Risk Factors for Recurrent Fetal Anomalies After a Previous Affected Pregnancy

After experiencing one pregnancy with a fetal anomaly, there is an increased risk of recurrence in subsequent pregnancies, with the specific risk depending on the type of anomaly, genetic factors, and other maternal conditions.

Risk Factors for Recurrent Fetal Anomalies

Genetic Factors

• Previous chromosomal disorders: Pregnancies with a history of chromosomal anomalies have a 1.76-fold increased risk of severe maternal morbidity in subsequent pregnancies 1
• Monozygotic twins: Have 2-3 times greater risk of congenital anomalies compared to singleton pregnancies 2

Type of Previous Anomaly

Different anomalies carry varying risks of recurrence:

• Neural tube defects (anencephaly, spina bifida): Associated with 2.20-3.27 times increased risk of complications in subsequent pregnancies 1
• Cardiac anomalies: Congenital heart disease is associated with a 2.66-fold increased risk of severe maternal morbidity 1
• Abdominal wall defects: Omphalocele carries a 3.15-fold increased risk 1

Maternal Factors

• Previous preterm prelabor rupture of membranes (PPROM): Nearly 50% of subsequent pregnancies after previable PPROM result in recurrent preterm birth, with 17% recurring at <24 weeks gestation 2
• Multiple previous preterm births: History of another preterm birth in addition to previable PPROM significantly increases recurrence risk 2
• Maternal age: Advanced maternal age increases risk of fetal anomalies in subsequent pregnancies 2

Pregnancy Management Factors

• Previous fetal surgery: Women who underwent open fetal surgery have higher risks in subsequent pregnancies:
  • 9.6% uterine rupture rate (comparable to classical cesarean) 2
  • 20% pregnancy loss before 24 weeks 2
  • 20.5% preterm birth in subsequent pregnancies 2
• Fetoscopic surgery: Lower but still significant risks:
  • 13.7% pregnancy loss before 24 weeks 2
  • 2.1% preterm birth in subsequent pregnancies 2

Surveillance and Management Recommendations

Preconception Care

• Comprehensive genetic counseling before attempting another pregnancy 3
• Optimization of maternal health conditions (diabetes, hypertension) 2
• Appropriate interpregnancy interval to reduce risks 2

Early Pregnancy Monitoring

• First trimester ultrasound with detailed assessment between 11-14 weeks 2
• Nuchal translucency (NT) screening for all pregnancies to screen for birth defects 2
• Consider cell-free DNA screening for chromosomal abnormalities 2

Second Trimester Management

• Detailed anatomy scan at 18-22 weeks with special attention to previously affected organ systems 2
• Consider fetal echocardiography if previous cardiac anomaly 2
• Cervical length assessment via transvaginal ultrasound to evaluate preterm birth risk 2

Special Considerations

• For women with previous previable PPROM, follow guidelines for management of pregnant persons with previous spontaneous preterm birth 2
• History-indicated cerclage should be reserved for individuals with classic features of cervical insufficiency or unexplained second-trimester loss without placental abruption 2
• Careful assessment for placenta accreta spectrum disorder in women with previous cesarean or uterine surgery 2

Mental Health Considerations

• Women with pregnancies complicated by fetal anomalies have significantly higher rates of anxiety (mean state anxiety score 43.6 vs 29.1) 2
• 5.5% of women with a pregnancy complicated by fetal anomaly are at high risk of traumatic stress 2
• 35.9% are at elevated risk of major depression in the immediate postpartum period 2
• Mental health support should be integrated into care plans 2

Pitfalls to Avoid

• Underestimating recurrence risk: Even with normal screening, certain anomalies have significant recurrence risk
• Inadequate monitoring: Failure to implement enhanced surveillance in subsequent pregnancies
• Overlooking maternal mental health: Anxiety and depression are common after a pregnancy with fetal anomaly
• Insufficient preconception counseling: Genetic counseling before subsequent pregnancy is essential
• Inappropriate cerclage use: Cerclage after previous previable PPROM may increase preterm birth risk (63.2% vs 10.9%) 2

By understanding these risk factors and implementing appropriate surveillance and management strategies, healthcare providers can help optimize outcomes for women with a history of fetal anomalies in previous pregnancies.