Prognosis of the co-twin following spontaneous single intrauterine fetal death in twin pregnancies: a systematic review and meta-analysis.

BACKGROUND: Single intrauterine fetal death affects approximately 6% of twin pregnancies and can have serious sequelae for the surviving co-twin.

OBJECTIVES: Determine the prognosis of the surviving co-twin following spontaneous single intrauterine fetal death to aid counselling patients and highlight future research areas.

SEARCH STRATEGY: Medline, Embase, Web of Science, and Cochrane Library, from 1980 to June 2017.

SELECTION CRITERIA: Studies of five or more cases of spontaneous single intrauterine fetal death after 14 weeks gestation, in diamniotic twin pregnancies.

DATA COLLECTION AND ANALYSIS: Summary event rates were calculated and stratified by chorionicity. Monochorionic and dichorionic twins, and sub-groups, were compared by odds ratios.

MAIN RESULTS: In monochorionic twins, when single intrauterine fetal death occurred at less than 28 weeks' gestation, this significantly increased the rate of co-twin intrauterine fetal death [odds ratio (OR) 2.31, 95% confidence interval (CI) 1.02-5.25, I2  = 0.0%, 12 studies, 184 pregnancies] and neonatal death (OR 2.84, 95% CI 1.18-6.77, I2  = 0.0%, 10 studies, 117 pregnancies) compared with when the single intrauterine fetal death occurred at more than 28 weeks' gestation. Neonatal death in monochorionic twins was significantly higher if the pregnancy was complicated by fetal growth restriction (OR 4.83, 95% CI 1.14-20.47, I2  = 0.0%, six studies, 60 pregnancies) or preterm birth (OR 4.95, 95% CI 1.71-14.30, I2  = 0.0%, 11 studies, 124 pregnancies). Abnormal antenatal brain imaging was reported in 20.0% (95% CI 12.8-31.1, I2  = 21.9%, six studies, 116 pregnancies) of surviving monochorionic co-twins. The studies included in the meta-analysis demonstrated small study effects and possible selection bias.

CONCLUSIONS: Preterm birth was the commonest adverse outcome affecting 58.5 and 53.7% of monochorionic and dichorionic twin pregnancies. Outcomes regarding brain imaging and neurodevelopmental comorbidity are an important area for future research, but meta-analysis may be limited due to different methods of assessment.

TWEETABLE ABSTRACT: Preterm birth is the highest risk in single co-twin death. Abnormal antenatal brain imaging was found in 1/5 surviving MC twins.