Outcome of twin pregnancies according to intrapair birth weight differences

Objective: To assess the clinical significance of twin intrapair birth weig ht differences. Methods: This was a retrospective study of twin pregnancy outcomes. Intrapa ir birth weight differences were stratified into the following six groups: 14% or less, 15-20%, 21-25%, 26-30%, 31-40%, and 41% or more using the larg er infant as the growth standard. Statistical analysis was done using the M antel-Haenzel chi(2) test. Results: We studied 1370 consecutive women who delivered at parkland Hospit al, Dallas, Texas, between January 1, 1988, and December 31, 1996, and had twin gestations and live births or fetal deaths within 7 days of delivery. Greater birth weight discordance was significantly associated with preterm delivery due to intervention (P <.001). Noncephalic-cephalic presentations and cesarean delivery were also associated with greater discordance (P =.00 1 and .02, respectively). Neonatal morbidities, including low birth weight, intensive care admission, and respiratory distress, were all associated wi th higher birth weight discordance. Fetal abnormalities were more common wi th increased discordance (P <.001). Greater birth weight discordance was al so associated with intrauterine fetal death. There were no differences in o utcome for the smaller compared with the larger twin of the twin pair. Conclusion: Twin birth weight discordance is problematic because severe div ergent fetal growth increases the risk of fetal death and leads to obstetri c intervention and consequent neonatal morbidity due to prematurity. (Obste t Gynecol 1999;94:1006-10. (C) 1999 by The American College of Obstetrician s and Gynecologists.).