RT Journal Article SR Electronic T1 Respiratory distress syndrome and birth order in premature twins JF Archives of Disease in Childhood - Fetal and Neonatal Edition JO Arch Dis Child Fetal Neonatal Ed FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP F117 OP F121 DO 10.1136/fn.84.2.F117 VO 84 IS 2 A1 D Hacking A1 A Watkins A1 S Fraser A1 R Wolfe A1 T Nolan YR 2001 UL http://fn.bmj.com/content/84/2/F117.abstract AB OBJECTIVE To determine the effect of birth order on respiratory distress syndrome (RDS) in the outcome of twins in a large premature population managed in a modern neonatal intensive care unit.METHODS An historical cohort study design was used to analyse the neonatal outcomes of 301 premature liveborn twin sibling pairs of between 23 and 31 weeks gestation from the Australia and New Zealand Neonatal Network 1995 database.RESULTS Among the 56 twin sibling pairs who were discordant for RDS, the second twin was affected in 41 cases (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.5 to 5.3). The excess risk of RDS in the second twin increased with gestation and was statistically significant for twins above 29 weeks gestation (OR 4.4, 95% CI 1.6 to 15).CONCLUSIONS There is a significant increased risk of RDS associated with being the second born of premature twins, which appears to depend on gestation.