{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,4]],"date-time":"2026-06-04T19:03:05Z","timestamp":1780599785022,"version":"3.54.1"},"reference-count":41,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2019,6,24]],"date-time":"2019-06-24T00:00:00Z","timestamp":1561334400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Monochorionic (MC) twins are at an increased risk of developing congenital heart defects (CHDs) compared to singletons and dichorionic twins. The development of acquired CHDs in this specific group of twins is associated with twin\u2013twin transfusion syndrome (TTTS). We performed a systematic review and meta-analysis to provide an overview of the reported birth prevalence of CHDs in liveborn MC twins with and without TTTS. Twelve studies were included in this review. Compared to the reference population, MC twins were 6.3 times more likely to be born with a CHD (59.3 per 1000 liveborn twins; relative risk (RR) 6.3; 95% confidence interval (CI): 4.4\u20139.1), and TTTS twins had a 12-fold increased risk of having a CHD at birth (87.3 per 1000 live births; RR 12.4, 95% CI: 8.6\u201317.8). The increased incidence of CHDs can mainly be attributed to the risk of right ventricular outflow tract obstruction (35\/1000 TTTS twin live births vs. 0.5\/1000 singleton live births). We recommend an expert fetal echocardiogram in all MC twins, follow-up scans in the event of TTTS, and a postnatal cardiac evaluation in all TTTS survivors.<\/jats:p>","DOI":"10.3390\/jcm8060902","type":"journal-article","created":{"date-parts":[[2019,6,24]],"date-time":"2019-06-24T16:52:51Z","timestamp":1561395171000},"page":"902","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":42,"title":["Congenital Heart Defects in Monochorionic Twins: A Systematic Review and Meta-Analysis"],"prefix":"10.3390","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5345-5701","authenticated-orcid":false,"given":"Manon","family":"Gijtenbeek","sequence":"first","affiliation":[{"name":"Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Center, PO Box 9600, NL-2300 RC Leiden, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maryam R.","family":"Shirzada","sequence":"additional","affiliation":[{"name":"Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Center, PO Box 9600, NL-2300 RC Leiden, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arend D. J.","family":"Ten Harkel","sequence":"additional","affiliation":[{"name":"Division of Pediatric Cardiology, Department of Pediatrics, Leiden University Medical Center, PO Box 9600, NL-2300 RC Leiden, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dick","family":"Oepkes","sequence":"additional","affiliation":[{"name":"Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Center, PO Box 9600, NL-2300 RC Leiden, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Monique","family":"C. Haak","sequence":"additional","affiliation":[{"name":"Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Center, PO Box 9600, NL-2300 RC Leiden, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2241","DOI":"10.1016\/j.jacc.2011.08.025","article-title":"Birth prevalence of congenital heart disease worldwide: A systematic review and meta-analysis","volume":"58","author":"Konings","year":"2011","journal-title":"J. Am. Coll. 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