Twin birth weight discordancy in Nigeria.

The perinatal outcomes for 56 birth-weight discordant twin pairs among 622 total twin deliveries that occurred over an 18-month period at the University of Ilorin Teaching Hospital are analyzed. The incidence of twin birth-size discordancy was 9%. Mean birth-weight (kg) was 2.78 +/- 0.5 for the heavier twin and 1.90 +/- 0.5 for the smaller twin, with a mean intra-pair birth-weight difference of 0.88 kg (31.7% of the heavier twin). Perinatal mortality in the smaller infants was increased above the mean for all twin births. There were no perinatal deaths among the heavier infants. Discordant twinning was associated with high parity and a disproportionate increase of unlike-sex pairs. These observations suggest the preponderance of discordancy in dizygotic twinning. Increased awareness and surveillance for discrepant twin pairs are suggested in order to improve perinatal outcome.