Main findings
The commonest associated aetiology with sIUFD in MC twin pregnancies was TTTS and the majority had undergone prenatal therapy prior to sIUFD (as opposed to being conservatively managed). The second most common aetiology was “spontaneous” with no obvious underlying aetiology (i.e. no signs of TTTS, sIUGR or congenital/structural anomaly), followed by congenital/structural anomaly, and sIUGR being the least common. Death of the co-twin following sIUFD was common, complicating 1 in 7 pregnancies. Less than two thirds of cases had investigation by antenatal CNS imaging to identify ischaemic brain injury. Of the cases whose imaging results were known to the UKOSS reporter, 1 in 5 had radiological findings suggestive of neurological morbidity. Postnatal CNS imaging revealed a further 7 babies with brain abnormalities (mainly on cranial USS), all of which were born at <36 weeks, and 4 of whom also had abnormal CNS signs. Preterm birth was the commonest adverse outcome, with three quarters of twins born at less than 37 weeks gestation, and an equal split between spontaneous preterm birth, and those delivered iatrogenically. Major maternal morbidity was not uncommon, with 6% requiring ITU admission, compared to 0.22% of the general obstetric population reported in the 2015/2016 National Maternity and Perinatal Audit18. Interestingly, all maternal admissions were related to sepsis, although not all women had undergone prenatal ‘invasive’ interventions for therapy.