OBJECTIVE: To investigate the association between chorionicity-specific intertwin birthweight (BW) discordance and adverse outcomes including long-term follow-up at 6, 18, and 48-60 months after term via Ages and Stages Questionnaire (ASQ).

MATERIAL AND METHODS: In this secondary analysis of a cohort study (Oldenburg et al,n=1688) and a randomized controlled trial (PREDICT study,n=1045) twin pairs were divided into three groups according to chorionicity-specific BW discordance; <75(th) -percentile, 75(th) -90(th) -percentile and >90(th) -percentile. Information on infant mortality, admittance to NICU, and gestational age at delivery was available for all pairs. Detailed neonatal outcomes were available for 656 pairs from PREDICT, of which 567 pairs had at least one ASQ follow-up. Logistic regression models were used for dichotomous outcomes. ASQ scores were compared using the method of generalized estimating equation to account for the correlation within twins.

RESULTS: The 75(th) and 90(th) -percentile for BW discordance were 14.8% and 21.4% for monochorionic and 16.0% and 23.8% for dichorionic twins. After adjustment for small for gestational age (SGA) and gender, BW discordance>75(th) and >90(th) -percentile was associated with induced delivery<34 weeks (OR 1.71 (95%CI 1.11;2.65) and OR 2.83 (1.73;4.64), respectively). Discordance>75(th) -percentile was associated with an increased risk of infant mortality after 28 days (OR 4.69 (1.07;20.45)) but not with major neonatal complications or with low mean ASQ scores at 6, 18, and 48-60 months after term.

CONCLUSION: Chorionicity-specific intertwin BW discordance is a risk factor for induced preterm delivery and infant mortality, but not for lower scores for neurophysiological development at 6, 18, and 48-60 months. This article is protected by copyright. All rights reserved.