Insecure attachment and internalizing behavior problems in growth discordant identical twins

Background: Psychosocial development in monochorionic (MC) twins born after selective fetal growth restriction (sFGR) has been unreported to date, despite its importance for daily functioning and future relationships.Aims: To investigate psychosocial development, attachment and school functioning in MC twins with sFGR and compare outcomes with the general population and between smaller and larger twins.Study design: Observational cohort study. Subjects: MC twins with sFGR (defined as a birth weight discordance >= 20 %) born between 2002 and 2017 and aged 3-17 years.Outcome measures: Multiple parent report questionnaires: the Child Behavior Checklist (social-emotional devel-opment and behavior), the (Early) Childhood Behavior Questionnaire Very Short Form (temperament), the Attachment Insecurity Screening Inventory (attachment) and a school functioning questionnaire.Results: Median age for the 48 twin pairs was 11 (interquartile range (IQR) 8-13) years. Attachment insecurity for both twins was higher than in the general population for ambivalence/resistance (34 % (21/62) vs. 16 %, p = 0.024) and total attachment insecurity (35 % (22/62) vs. 16 %, p = 0.016). Smaller twins had more internalizing behavioral problems, i.e. negative emotions and behaviors turned inwards (22 % (10/46) vs. 11 % (5/46), p = 0.021) and a higher negative affect, i.e. more likely to experience negative emotions (3.2 (2.9-3.7) vs. 2.9 (2.2-3.2), p = 0.009) than larger twins, as well as a lower secondary school level (p = 0.031).Conclusion: MC twins with sFGR have more ambivalent/resistant attachment insecurity following the compli-cated pregnancy course. Smaller twins have a tendency towards negative emotions and internalizing behaviors compared to larger twins, indicating an increased sensitivity for depression and anxiety.

Automated summary

This study investigated the psychosocial development of monochorionic twins born after selective fetal growth restriction (sFGR) and found that they had a higher level of attachment insecurity and school problems. Smaller twins were more prone to negative emotions and internalizing behaviors compared to larger twins.