Twin delivery: influence of the presentation and method of delivery on the second twin.

To ascertain the perinatal mortality and morbidity in the second twin as related to its presentation and method of delivery, we reviewed the data on 578 sets of twins delivered from 1980 to 1987 and included 397 sets in whom both twins were greater than or equal to 1000 gm, without lethal anomalies, and in whom the first twin presented as a vertex. The perinatal outcome comparing twin A (all vertex) with twin B (vertex or nonvertex) with cesarean section or vaginal delivery was analyzed. No statistically significant difference in perinatal mortality or morbidity was found in comparing the nonvertex second twin delivered vaginally or by cesarean section. The one perinatal death and significant perinatal morbidity occurred in infants weighing less than 1500 gm or at less than 32 weeks' gestational age. It is concluded that vaginal delivery, irrespective of the position of the second twin, is valid in selected cases as long as fetal weight is greater than 1500 gm and the gestational age is greater than or equal to 32 weeks.