Objective: Second-born twin outcome was compared with that of the first-twin birth mate to determine whether there were differences, the reason for the differences, if any, and the clinical decisions that could be made to eliminate or ameliorate these differences.
Study design: Twin pregnancies from 1989 through 1992 were retrospectively reviewed. Charts demonstrating both twins stillborn, either twin weighing < 500 gm, or either twin with a serious congenital anomaly were excluded from evaluation. After these exclusions 200 twin pairs remained for analysis. Each twin was compared directly with its birth mate. The first twin is postulated as having the best possible outcome for the pregnancy involved, and second-twin outcomes are compared with these.
Results: The second-born twin was more likely to be intubated, have respiratory distress syndrome, need resuscitation, and have lower 5-minute Apgar scores. Second-born twins had more nursery complications. The < 1500 gm group appeared to be at special risk. In this group there were more second-born twin neonatal deaths and much higher rates of intubation and resuscitation. Nonvertex presentation in the second-born twin increased chances for resuscitation, intubation, respiratory distress syndrome, and nursery complications. These outcomes in the second-born were not affected by cesarean delivery.
Conclusions: The second-born twin is at increased risk of untoward outcome compared with its birth mate. Some of this risk can be attributed to birth weight. The risk posed by nonvertex presentation is small. Cesarean section delivery does not appear to eliminate the difference between first- and second-twin outcome. Prospective studies are needed.