Discordancy in triplets

Discordancy in twins is generally described as a weight difference between the fetuses of 15 to 25% and its prevalence in normal twin gestations is estimated at 15 to 29%. The present study was performed in order to determine the frequency of discordant newborns in uncomplicated triplet gestations. One hundred and fourteen normal triplet newborns were delivered during a period of 11 years. Their birthweight ranged from 493 to 2533 gm, with a mean of 1894.2 +/- 468.5 gm (+/- sd). In 58% of these 38 sets of triplets the difference in weight between the largest and smallest newborn was more than 15%. About a quarter of the newborns had a greater than 25% dissimilarity in their birthweights. There was no substantial fetal-fetal transfusion or difference in the Apgar scores between the discordant fetuses. It may be concluded that triplet newborns have a rate of discordancy double that of twins. Discordance per se does not necessarily mark an underlying complication of pregnancy or a bad perinatal outcome.