{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T19:01:53Z","timestamp":1785438113600,"version":"3.56.0"},"reference-count":50,"publisher":"Cambridge University Press (CUP)","issue":"2","license":[{"start":{"date-parts":[[2026,6,5]],"date-time":"2026-06-05T00:00:00Z","timestamp":1780617600000},"content-version":"unspecified","delay-in-days":65,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["cambridge.org"],"crossmark-restriction":true},"short-container-title":["Twin Res Hum Genet"],"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Twin studies provide a powerful framework to identify genetic and environmental influences on health and development, particularly during infancy, childhood, and adolescence. Although twin research has expanded globally, evidence from South Asia remains limited and poorly characterized. This systematic review aimed to synthesize health research involving infant, child, and adolescent twins conducted in South Asia and to identify methodological patterns and research gaps relevant to future twin research in the region. A systematic review was conducted according to a registered protocol (PROSPERO: CRD42018105704) using the PICOS framework. Multiple international and regional databases were searched from inception to September 2025. Studies recruiting twins aged 0\u201319 years within the South Asian Association for Regional Cooperation (SAARC) countries were included. Study selection, data extraction, and quality appraisal were conducted independently, with study quality assessed using Joanna Briggs Institute critical appraisal tools. Results were synthesized narratively due to heterogeneity across study designs and outcomes. Eighteen studies were included from 1245 identified records. Most studies focused on twin pregnancy and neonatal outcomes (61%), followed by dentistry, ocular health, and gut microbiota. Twin pregnancies were consistently associated with increased risks of low birth weight, preterm birth, and perinatal morbidity and mortality. A limited number of studies applied classical twin designs to investigate genetic and environmental contributions. Twin research involving infants, children, and adolescents in South Asia remains limited in scope and methodological depth. Strengthening twin registries, methodological standardization, and collaborations is essential to advance genetically informative research and enhance the global representativeness of twin studies.<\/jats:p>","DOI":"10.1017\/thg.2026.10062","type":"journal-article","created":{"date-parts":[[2026,6,5]],"date-time":"2026-06-05T06:19:22Z","timestamp":1780640362000},"page":"108-117","update-policy":"https:\/\/doi.org\/10.1017\/policypage","source":"Crossref","is-referenced-by-count":0,"title":["A Systematic Review of Twin Studies in Infants, Children, and Adolescents in Health Research: Focus on South Asia"],"prefix":"10.1017","volume":"29","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7114-3795","authenticated-orcid":false,"given":"Janani","family":"Opatha","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00691gs61","id-type":"ROR","asserted-by":"publisher"}],"name":"Institute for Research and Development in Health and Social Care"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lasith","family":"Dissanayake","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00691gs61","id-type":"ROR","asserted-by":"publisher"}],"name":"Institute for Research and Development in Health and Social Care"},{"name":"University of South Wales"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oshini Sri","family":"Jayasinghe","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00691gs61","id-type":"ROR","asserted-by":"publisher"}],"name":"Institute for Research and Development in Health and Social Care"},{"name":"University of Liverpool"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Binoli","family":"Herath","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00691gs61","id-type":"ROR","asserted-by":"publisher"}],"name":"Institute for Research and Development in Health and Social Care"},{"name":"Arizona State University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alina","family":"Andras","sequence":"additional","affiliation":[{"name":"Centre for Tropical Livestock Genetics and Health, University of Edinburgh"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sameeha","family":"Jabir","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00691gs61","id-type":"ROR","asserted-by":"publisher"}],"name":"Institute for Research and Development in Health and Social Care"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P.R. 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