Intrauterine death of one fetus in a twin pregnancy is uncommon in the second or third trimester. However, the consequences to the surviving co-twin can be profound, especially in monochorionic twins. These may include co-twin death, survival with cerebral impairment or preterm labour with its sequelae.1 Recent changes in technology and prenatal ultrasound scan have meant that clinicians can diagnose this condition and have the option to intervene. Decision making should be informed by existing prognostic evidence, but individual studies including data from case reports, follow up of cohorts and twin registries tend to have imprecise results as the event is uncommon. More precise information may be obtained by pooling these results statistically in a meta-analysis. A comprehensive systematic review is required to capture the literature scattered across many journals. Thus far, existing reviews2,3 have not been systematic and this may be because the methodology of meta-analysis involving observational studies is not widely disseminated. We conducted such a review to provide a reliable estimate of prognosis for the co-twin following single-twin death after the first trimester of pregnancy.