Definition of Intertwin Birth Weight Discordance

Authors:
  • FMFionnuala M. McAuliffe
    Fionnuala M. McAuliffe
  • MGMichael Geary
    Michael Geary
  • SDSean Daly
    Sean Daly
  • JHJohn R. Higgins
    John R. Higgins
  • JDJames Dornan
    James Dornan
  • JMJohn J. Morrison
    John J. Morrison
  • SHShane Higgins
    Shane Higgins
  • PDPatrick Dicker
    Patrick Dicker
  • FMFiona Manning
    Fiona Manning
  • RMRhona Mahony
    Rhona Mahony
Publisher website
Google Scholar
Abstract
To establish the level of birth weight discordance at which perinatal morbidity increases in monochorionic and dichorionic twin pregnancy. This prospective multicenter cohort study included 1,028 unselected twin pairs recruited over a 2-year period. Participants underwent two weekly ultrasonographic surveillance from 24 weeks of gestation with surveillance of monochorionic twins two-weekly from 16 weeks. Analysis using Cox proportional hazards compared a composite measure of perinatal morbidity (including any of the following: mortality, respiratory distress syndrome, hypoxic-ischemic encephalopathy, periventricular leukomalacia, necrotizing enterocolitis, or sepsis) at different degrees of birth weight discordance with adjustment for chorionicity, gestational age, twin-twin transfusion syndrome, birth order, gender, and growth restriction. Perinatal outcome data were recorded for 977 patients (100%) who continued the study with both fetuses alive beyond 24 weeks, including 14 cases of twin-twin transfusion syndrome. Adjusting for gestation at delivery, twin order, gender, and growth restriction, perinatal mortality, individual morbidity, and composite perinatal morbidity were all seen to increase with birth weight discordance exceeding 18% for dichorionic pairs (hazard ratio 2.2, 95% confidence interval [CI] 1.6-2.9, P<.001) and 18% for monochorionic twins without twin-twin transfusion syndrome (hazard ratio 2.6, 95% CI 1.6-4.3, P<.001). A minimum twofold increase in risk of perinatal morbidity persisted even when both twin birth weights were appropriate for gestational age. : The threshold for birth weight discordance established by this prospective study is 18% both for dichorionic twin pairs and for monochorionic twins without twin-twin transfusion syndrome. This threshold is considerably lower than that defined by many retrospective series as pathologic. We suggest that an anticipated difference of 18% in birth weight should prompt more intensive fetal monitoring.

This publication has 20 references indexed in Scilit: