RESUMEN
OBJECTIVE: To examine the rates of discordance in neonatal risk factors and neurodevelopmental outcomes within very low birth weight twin pairs and the factors associated with discordant outcomes. STUDY DESIGN: Rates of neonatal risk factors and neurodevelopmental outcomes, and discordance in outcomes were examined for 88 very low birth weight twin pairs born between 1990 and 2005 and followed through 20 months' corrected age. RESULT: Discordance rates ranged from 17 to 42% for neonatal risk factors and from 18 to 31% for neurodevelopmental outcomes. In regression analysis, affected co-twins were significantly more likely to have had an abnormal cerebral ultrasound than their unaffected co-twins in pairs discordant for cerebral palsy (odds ratio (OR): 13.00, 95% confidence interval (CI): 2.22 to 76.03)) and in pairs discordant for neurodevelopmental impairment (OR: 4.00, 95% CI: 1.13 to 14.18). Outcomes and discordance in outcomes were similar for monochorionic and dichorionic pairs. CONCLUSION: Despite shared genetics and risk factors, twins may have discordant outcomes. Information on discordant neonatal and neurodevelopmental outcomes is important for counseling families of twins.