Objective: This study was undertaken to assess the risk of neonatal morbidity in the second twins.
Study design: We carried out a cohort study of 128,219 live born second twins in the United States, 1995 through 1997. The study subjects were divided into 3 groups: second twins delivered by cesarean section after vaginal delivery of the first twin (V-C), both twins delivered vaginally (V-V), and both twins delivered by cesarean section (C-C).
Results: The rates of low 5-minute Apgar score, mechanical ventilation, and seizure were higher in the V-C group (8.27%, 13.39%, and 0.31%) than in the V-V (3.07%, 7.51%, and 0.08%) and the C-C (2.66%, 8.53%, and 0.06%) groups. The V-C associated increase in risk remained after adjustment for confounding factors and was more evident at term than preterm.
Conclusion: The risk of neonatal morbidity is increased in second twins who had a cesarean section after vaginal delivery of the first twin, especially at term.