Background : Second twin delivery has been associated with poor perinatal outcome such as birthasphyxia ,neonatal ICU admission and perinatal death in comparison to the first twin. here is limitedinformation on the perinatal outcome of second twin in Tanzania. This study aimed at determining theperinatal outcome associated with second twin delivery in a tertiary hospital in Northern Tanzania.

Methods: A retrospective cross-sectional study was conducted in a Tanzanian northern zone tertiaryhealth facility using existing maternal linked data from medical birth registry. Women with twin deliveriesfrom 2000 to 2015 were recruited. Adverse perinatal outcomes associated with second twin deliverieswere estimated using multivariable logistic regression models. A p-value of < 0.05 was consideredstatistically signi

Results : Retention rate of second twin was 18.6% (n=265). Out of the 265 retained second twins, 54.7%were referral cases, majority of which came from district hospitals. Retained second twins had 1.54 ( 95%CI 1.08-2.20) and 2.49( 95% CI 1.14-5.48) higher odds of lower Apgar scores in the 5 th minute andperinatal death when compared to non-retained twins respectively. Referral cases had poor outcomecompared to non-referrals. Retained twin who had caesarean section had lower odds of low Apgar scoresin the 5 th minute, perinatal death and Neonatal intensive care admission although this was notstatistically significant but clinically significant.

Conclusion : Rate of retained second twin is high in this setting, most of which are referral cases. Theretained second twin is associated with higher risk for perinatal death and low Apgar score in the 5 thminute. Timely delivery by caesarean section has lower chances of perinatal death, Neonatal intensivecare admission and low Apgar scores. Therefore, early diagnosis and/or referral of twin pregnancycoupled with timely and appropriate intervention for delivery of the retained second twin will contribute toreduction in perinatal morbidity and mortality.