The incidence, maternal, fetal and neonatal consequences of single intrauterine fetal death in monochorionic twins: A prospective observational UKOSS study.

OBJECTIVE Report maternal, fetal and neonatal complications associated with single intrauterine fetal death (sIUFD) in monochorionic twin pregnancies. DESIGN Prospective observational study. SETTING UK. POPULATION 81 monochorionic twin pregnancies with sIUFD after 14 weeks gestation, irrespective of cause. METHODS UKOSS reporters submitted data collection forms using data from hospital records. MAIN OUTCOME MEASURES Aetiology of sIUFD; surviving co-twin outcomes: perinatal mortality, central nervous system (CNS) imaging, gestation and mode of delivery, neonatal outcomes; post-mortem findings; maternal outcomes. RESULTS The commonest aetiology was twin-twin transfusion syndrome (38/81, 47%), "spontaneous" sIUFD (22/81, 27%) was second commonest. Death of the co-twin was common (10/70, 14%). Preterm birth (<37 weeks gestation) was the commonest adverse outcome (77%): half were spontaneous and half iatrogenic. Only 46/75 (61%) cases had antenatal CNS imaging, of which 33 cases had known results of which 7/33 (21%) had radiological findings suggestive of neurological damage. Postnatal CNS imaging revealed an additional 7 babies with CNS abnormalities, all born at <36 weeks, including all 4 babies exhibiting abnormal CNS signs. Major maternal morbidity was relatively common, with 6% requiring ITU admission, all related to infection. CONCLUSIONS Monochorionic twin pregnancies with single IUD are complex and require specialist care. Further research is required regarding optimal gestation at delivery of the surviving co-twin, preterm birth prevention, and classifying the cause of death in twin pregnancies. Awareness of the importance of CNS imaging, and follow-up, needs improvement.