Intrapair birthweight discordance in twins.

BACKGROUND Birthweight differences in twin pairs influence their perinatal outcome as well as growth and development. Growth-discordant twins have not been well characterized in our local environment. OBJECTIVE To determine the frequency of birthweight discordance in live-born twin pairs and document some factors that may influence it. METHODS In this cross-sectional study, 104 live-born twin pairs were recruited and their intrapair birthweight differences were determined. Twin pairs whose birthweight difference was 15% or more, using the larger infant as the growth standard, were designated as discordant. The maternal age, parity, and birth order of the heavier twin were noted. RESULTS The prevalence of birthweight discordance was 28.8% when a 15% cut-off point was used but dropped to 9.6% when a 25% cut-off point was applied. Grand multiparity was associated with a significantly increased risk of delivery of discordant twins. Same-sex twin pairs accounted for 60% of all cases of birthweight discordance. CONCLUSION Birthweight discordance is common in twin gestations in Benin City, especially among grand multiparous women.