{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T15:13:45Z","timestamp":1784042025896,"version":"3.55.0"},"reference-count":48,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2025,6,5]],"date-time":"2025-06-05T00:00:00Z","timestamp":1749081600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,6,5]],"date-time":"2025-06-05T00:00:00Z","timestamp":1749081600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100000050","name":"National Heart, Lung, and Blood Institute","doi-asserted-by":"publisher","award":["R01\u2010HL150065"],"award-info":[{"award-number":["R01\u2010HL150065"]}],"id":[{"id":"10.13039\/100000050","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000066","name":"National Institute of Environmental Health Sciences","doi-asserted-by":"publisher","award":["R01\u2010ES033190"],"award-info":[{"award-number":["R01\u2010ES033190"]}],"id":[{"id":"10.13039\/100000066","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000049","name":"National Institute on Aging","doi-asserted-by":"publisher","award":["R01\u2010AG056479"],"award-info":[{"award-number":["R01\u2010AG056479"]}],"id":[{"id":"10.13039\/100000049","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000030","name":"Centers for Disease Control and Prevention","doi-asserted-by":"publisher","award":["U01\u2010DD001293"],"award-info":[{"award-number":["U01\u2010DD001293"]}],"id":[{"id":"10.13039\/100000030","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Paediatric Perinatal Epid"],"published-print":{"date-parts":[[2026,2]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Generally, studies in perinatal epidemiology restrict cohort entry to 20\u2009weeks of gestation, but exposures and outcomes may occur earlier. This restriction may introduce left truncation bias.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To examine the impact of left truncation bias when estimating the causal effect of abruption on perinatal mortality in the context of abnormal placentation, with spontaneous abortion (SAB) as a censoring event.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Through 80 Monte Carlo simulation scenarios based on realistic clinical assumptions, we estimated risk differences (RD), risk ratios (RR) and bias parameters for the abruption\u2013perinatal mortality association.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Censoring by SAB ranged from 5.6% to 7.6% across simulation setups. The risk of mortality was overestimated in observable (left\u2010truncated) data at \u2265\u200920\u2009weeks compared to an unobservable cohort starting follow\u2010up at placental implantation (conception cohort). Underestimation of risks was stronger among abruption pregnancies. RDs for the abruption\u2010mortality association were biased by +1% to +3% among conceptions with normal implantation and by +5% to +43% among abnormal placentation. Due to the disproportionate underestimation of mortality among nonabruption pregnancies, RRs were overestimated by 1.1 to 1.2\u2010fold for normal implantations and by 1.1 to 8.4\u2010fold for abnormal implantations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The findings of this simulation study highlight the critical importance of placentation in successful pregnancy. Abnormal placentation has profound consequences for unsuccessful pregnancies, remarkably increasing the risks of early losses, placental abruption and other obstetrical complications. This study underscores that left truncation can bias the abruption\u2013perinatal mortality association, differentially by whether the placentation was normal or abnormal. However, defining the causal question regarding the abruption\u2013perinatal mortality association requires consideration of the target population, which may include all conceptions. In studies of these effects, outcome follow\u2010up capability may introduce left truncation bias. We do not prescribe one analytic approach to account for left truncation, but rather, the approach should be guided by the causal question.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/ppe.70010","type":"journal-article","created":{"date-parts":[[2025,6,5]],"date-time":"2025-06-05T11:30:42Z","timestamp":1749123042000},"page":"133-143","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Placental Abruption and Perinatal Mortality: Abnormal Placentation and Spontaneous Abortion as Contributors to Left Truncation Bias"],"prefix":"10.1111","volume":"40","author":[{"given":"Alan C.","family":"Kinlaw","sequence":"first","affiliation":[{"name":"Division of Pharmaceutical Outcomes and Policy University of North Carolina School of Pharmacy  Chapel Hill North Carolina USA"},{"name":"Cecil G. Sheps Center for Health Services Research University of North Carolina  Chapel Hill North Carolina USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hillary L.","family":"Graham","sequence":"additional","affiliation":[{"name":"Clinical Epidemiology Division, Faculty of Medicine at Solna Karolinska Institutet  Stockholm Sweden"},{"name":"Division of Epidemiology and Biostatistics, Department of Obstetrics, Gynecology, and Reproductive Sciences Rutgers Robert Wood Johnson Medical School  New Brunswick New Jersey USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0410-2595","authenticated-orcid":false,"given":"Cande V.","family":"Ananth","sequence":"additional","affiliation":[{"name":"Division of Epidemiology and Biostatistics, Department of Obstetrics, Gynecology, and Reproductive Sciences Rutgers Robert Wood Johnson Medical School  New Brunswick New Jersey USA"},{"name":"Department of Biostatistics and Epidemiology Rutgers School of Public Health  Piscataway New Jersey USA"},{"name":"Cardiovascular Institute of New Jersey Rutgers Robert Wood Johnson Medical School  New Brunswick New Jersey USA"},{"name":"Environmental and Occupational Health Sciences Institute (EOHSI) Rutgers Robert Wood Johnson Medical School  New Brunswick New Jersey USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,6,5]]},"reference":[{"key":"e_1_2_11_2_1","doi-asserted-by":"publisher","DOI":"10.1097\/01.AOG.0000239439.04364.9a"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1053\/j.semperi.2014.03.001"},{"key":"e_1_2_11_4_1","volume-title":"UpToDate","author":"Ananth C. 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