Outcome of twin pregnancies with extreme weight discordancy.

The objective of this paper is to examine the outcome of pregnancies with extreme weight-discordant twins. Percentage of birth weight discordancy was defined as the birth weight difference between the twins divided by the larger twin's weight and multiplied by 100. Discordancy was calculated for all twin births in which both fetuses were live born. In 33 pairs, the discordancy was defined as extreme (>35%) and they constituted the study group. Thirty-three pairs of twin defined with mild weight discordancy (15-25%), and 33 pairs defined as concordant to birth weight (<15% difference) were matched to the study group patients based on gestational age at delivery (+/- 7 days) and on the mode of delivery, and constituted the control groups. The records of all the patients were reviewed for pregnancy complications and for major and minor neonatal outcome variables. Significantly more parturients in the study groups were primiparous undergoing in vitro fertilization treatments to conceive. Significantly more women in the study group had severe preeclampsia compared with women with mild discordancy or concordant twins (12.1 vs. 3.0% and 0%, respectively, p <0.025). No significant differences were encountered between the groups in neonatal mortality or morbidity factors except an increased rate of hyperbilirubinemia in the study group, p = 0.006. Using logistic regression analysis, discordancy was not defined as an efficient predictor for adverse neonatal outcome. Twin pregnancies with extreme discordancy have a favorable neonatal outcome in correlation with gestational age and not with the percentage of discordancy.