Perinatal outcome after single intrauterine death in monochorionic twin pregnancy: systematic review and meta‐analysis

Objective To report perinatal and neurodevelopmental outcomes in monochorionic twin pregnancy after single intrauterine fetal death (IUFD), according to gestational age at single IUFD and the presence of twin-twin transfusion syndrome (TTTS). Methods MEDLINE, EMBASE and The Cochrane Library were searched for studies reporting the outcome of monochorionic twin pregnancy complicated by single IUFD. The collected outcomes included preterm birth (PTB) < 34, < 32 and < 28 weeks' gestation, cotwin IUFD and neonatal death (NND), cerebral anomaly detected at follow-up prenatal ultrasound examination, fetal magnetic resonance imaging (MRI) or postnatal imaging (ultrasound or MRI) and adverse neurodevelopmental outcome. Subgroup analyses were conducted according to the presence of TTTS and gestational age at single IUFD. We reported the association of various risk factors, namely signs of fetal anemia, TTTS and selective fetal growth restriction (sFGR), with the risk of abnormal brain imaging. Random-effects meta-analysis of proportions was used to analyze the data, and results were reported as pooled proportions or odds ratios (ORs) with 95% CI. Results Twenty-three studies, comprising 1294 monochorionic twin pregnancies complicated by single IUFD, were included. PTB < 34, < 32 and < 28 weeks' gestation occurred in 45.8% (95% CI, 34.0-57.8%), 28.0% (95% CI, 16.3-41.4%) and 10.9% (95% CI, 5.6-17.6%) of cases, respectively. Cotwin IUFD and NND were reported in 6.2% (95% CI, 2.6-11.0%) and 4.1% (95% CI, 2.6-5.9%) of cases, respectively. Cerebral anomaly at fetal MRI was reported in 20.0% (95% CI, 14.2-26.4%) of cases, most of which were severe. Adverse neurodevelopmental outcome was documented in 11.0% (95% CI, 4.7-19.6%) of infants, but in none of those with normal prenatal imaging. When comparing pregnancies without TTTS to those with TTTS that did not undergo laser therapy, PTB < 34 weeks occurred in 47.7% (95% CI, 29.8-65.9%) and 40.0% (95% CI, 17.2-65.4%), respectively. The corresponding figures for cotwin IUFD were 7.3% (95% CI, 1.4-17.3%) and 5.7% (95% CI, 0.4-23.2%); those for cotwin NND were 2.5% (95% CI, 0.6-5.6%) and 13.9% (95% CI, 3.9-28.7%); and those for adverse neurodevelopmental outcome were 34.5% (95% CI, 5.1-73.3%) and 34.5% (95% CI, 12.5-60.8%). Signs of fetal anemia in the surviving fetus were associated with significantly higher odds of abnormal brain imaging (OR, 4.3 (95% CI, 1.7-10.9); P = 0.003), while TTTS (P = 0.104) and sFGR (P = 0.283) were not associated with higher odds of cerebral anomaly on imaging. Conclusions Single IUFD in monochorionic twin pregnancy is associated with high risks of PTB, abnormal brain imaging and adverse neurodevelopmental outcome in the surviving cotwin, although the risks are lower than those reported previously. All cotwins with normal prenatal imaging had normal neurodevelopment, highlighting the prognostic role of prenatal brain assessment after single IUFD. (c) 2025 International Society of Ultrasound in Obstetrics and Gynecology.