Intergenerational Risk and Resilience of Rohingya in Displacement

Overview

The iRRRd study is an ongoing prospective longitudinal prenatal birth cohort study based in Cox's Bazar, Bangladesh. Between February 2023 and March 2024, 2,888 pregnant women were enrolled (approximately 80% Rohingya refugees living in camps, 20% Bangladeshi host community). The study aims to investigate (1) the effects of being conceived, gestated, born, and raised in contexts of conflict and forced displacement on child health and development; (2) the mechanisms underlying the intergenerational transmission of conflict and displacement trauma to offspring; and (3) the sources of heterogeneity in these associations across individual, social, biological, and contextual risk and protective factors. Five waves of data collection have been completed: prenatal recruitment (Wave 1), third-trimester follow-up for a subset of the sample (Wave 2), birth (Wave 3), 28 days postpartum (Wave 4), and 6 months postpartum (Wave 5, completed April 2025; N=2,526). This registration covers Wave 6, the 36-month follow-up, in which target children are assessed when they reach 36 months of age. Anticipated enrollment for this wave is approximately 2,200 mother-child dyads. Waves 1-5 were conducted without preregistration due to logistical and timing constraints inherent to launching large-scale research in a complex humanitarian context. Design and preparation for the 36-month wave began in June-July 2025, and field piloting of study procedures and measures began in September 2025. Follow-ups with children reaching 36 months of age began in late May 2026. The original planning estimate of March 2026 reflected the 36-month mark for the earliest-born children in the cohort (first births occurred in March 2023); the ±2-month eligibility window (Part 5) accommodated the modest delay to actual fieldwork start. Up to the first week of August, fieldwork progressed slowly with a smaller number of enumerators, as several measures were still being refined and modified based on ongoing piloting. We consider this wave officially launched once onboarding and training of an expanded group of data collectors is complete and the pace of follow-ups picks up with number of children turning 36 months of age. All field activities that predate this registration are considered piloting and have served to iron out remaining logistical, technical, and language issues, and to finalize decisions on tool and item selection. No data have been analyzed, with the exception of measures for which psychometric properties needed to be examined to inform modification and selection decisions.

Background and rationale. By 2024, an estimated 117.8 million people globally had been forcibly displaced by persecution, armed conflict, or other human rights violations (UNHCR, 2026). The vast majority reside in low- and middle-income countries (LMICs). The Rohingya refugees in Cox's Bazar, Bangladesh - numbering over one million - represent one of the world's largest and longest-standing refugee populations. A substantial body of research has established that exposure to trauma and adversity before and during pregnancy can affect offspring development through neurobiological mechanisms including fetal programming and intergenerational epigenetic transmission, as well as through postnatal disruptions to caregiving. Despite the scale of this global challenge, large-scale longitudinal studies of early child development in humanitarian contexts that begin prenatally remain extremely rare. The iRRRd study was designed to address this gap. Drawing on Bronfenbrenner and Morris' bioecological systems framework, it captures risk and protective factors spanning multiple levels - from molecular processes to household and family dynamics to broader contextual forces such as camp governance, humanitarian infrastructure, and environmental stressors - through a multi-method, interdisciplinary approach combining qualitative, survey, observational, physiological, and neurobiological data. The 36-month wave. The 36-month time point is a critical developmental window: cognitive, language, social-emotional, and behavioral development can be more reliably measured using gold-standard instruments; executive function (EF) emerges as a distinct and predictive construct; and caregiver-child playful interactions become more observable and directly relevant to developmental outcomes. This wave extends the longitudinal scope from infancy into toddlerhood, enabling examination of developmental trajectories from the prenatal period through early childhood. A central scientific focus of this wave is the role of play and playful caregiver-child interactions as a source of resilience. Preliminary data from older siblings of enrolled children suggest that playful interactions buffer EF development specifically when mothers are experiencing elevated psychological distress. The 36-month wave allows formal testing of this and related hypotheses with the target cohort. Key hypotheses. Guided by the bioecological framework above, this wave is designed to test several related hypotheses: (H1) caregiver-child playful interaction quality will buffer the association between maternal psychological distress and child cognitive/executive function outcomes, such that the association is attenuated at higher observed play quality; (H2) maternal executive function and autonomic regulation (HRV) will each independently predict caregiver-child interaction quality, which will in turn mediate the association between maternal functioning and child developmental outcomes; (H3) child psychosocial adversity (CPAS) will be associated with poorer child cognitive, executive function, and behavioral outcomes, and this association will be moderated by caregiver mental health and caregiving quality; (H4) physiological synchrony between mother and child during the caregiver-child interaction observation, indexed by concurrent HRV, will be positively associated with interaction quality and, secondarily, with child self-regulation outcomes. These hypotheses will be tested using the primary and secondary outcomes and the predictor, mediator, and moderator measures specified above. Exploratory biological analyses. In parallel with the confirmatory hypotheses above, the study maintains a biobank of saliva and buccal swab specimens (described in Part 4) that will support exploratory, hypothesis-generating analyses as funding and laboratory capacity permit. Planned exploratory work includes untargeted and targeted proteomic and metabolomic profiling (e.g., inflammatory markers, steroid hormones including cortisol, oxylipins) and epigenetic analyses (e.g., DNA methylation, telomere length). Because the analytic pipelines, sample subsets, and quality-control criteria for these assays are still being finalized, this work is not registered as formal outcome measures in this record. Findings will be reported as exploratory, and specific analyses will be preregistered separately on a per-study basis once hypotheses and analytic plans are finalized. Note on timing of registration. The iRRRd study began in 2023 and was not preregistered at inception due to logistical and timing constraints inherent to launching large-scale research in a complex humanitarian context. This registration is filed prospectively with respect to the 36-month data collection wave. See Brief Summary for details on the timing of registration relative to fieldwork. Data from Waves 1-5 were collected without registration; analyses of those data are not governed by this registration, though individual papers are being preregistered on an individual basis.