The effect of chorionicity and twin-to-twin delivery time interval on short-term outcome of the second twin

Abstract Objectives: To investigate the effect of chorionicity and twin-to-twin delivery time interval on short-term outcome in the second twin. Additionally, to investigate predictors of adverse outcome in both twins. Methods: Data included vaginally delivered twins (≥ 36 weeks) from Copenhagen University Hospitals (2001-09). The association between delivery interval and adverse outcome parameters were compared for monochorionic (MC) and dichorionic (DC) twins by multiple linear regression. Predictors were studied by logistic regression. Results: There were 554 twin pairs: 57 MC and 485 DC. We found no difference in the decrease of pH (p = 0.912) and Apgar (p = 0.609) in relation to increasing time interval. Neonatal unit (NICU) admissions did not differ (p = 0.167). Apgar ≤ 7 (p <0.001) and pH ≤ 7.20 (p = 0.002) increased first twin, whereas first (p = 0.001) or second (p <0.001) twin Apgar ≤ 7 and second twin pH ≤ 7.00 (p = 0.003) increased second twin risk of NICU admission. Conclusions: Increasing delivery interval was associated with a significant decrease in pH and Apgar, but there was no difference between MC and DC twins. Low Apgar of the first twin increased the risk of second twin NICU admission.