{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T05:45:21Z","timestamp":1789623921751,"version":"build-2803163510"},"reference-count":37,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2015,7,21]],"date-time":"2015-07-21T00:00:00Z","timestamp":1437436800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/501100004359","name":"Vetenskapsr\u00e5det","doi-asserted-by":"publisher","award":["2011-3060"],"award-info":[{"award-number":["2011-3060"]}],"id":[{"id":"10.13039\/501100004359","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003793","name":"Hj\u00e4rt-Lungfonden","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100003793","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Swedish Initiative for research on Microdata in the Social And Medical Sciences (SIMSAM)","award":["340-2013-5867"],"award-info":[{"award-number":["340-2013-5867"]}]},{"DOI":"10.13039\/501100004348","name":"Stockholm County Council","doi-asserted-by":"crossref","award":["ALF project"],"award-info":[{"award-number":["ALF project"]}],"id":[{"id":"10.13039\/501100004348","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Strategic Research Program in Epidemiology at Karolinska Institutet"},{"name":"Swedish Asthma and Allergy Association\u2019s Research Foundation."}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Clin Experimental Allergy"],"published-print":{"date-parts":[[2015,8]]},"abstract":"<jats:title>Summary<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      Children born with low gestational age (\n                      <jats:styled-content style=\"fixed-case\">GA<\/jats:styled-content>\n                      ) or low birthweight (\n                      <jats:styled-content style=\"fixed-case\">BW<\/jats:styled-content>\n                      ) are at increased risk of asthma. Twins as compared to singletons are on average more likely to be born with lower\n                      <jats:styled-content style=\"fixed-case\">GA<\/jats:styled-content>\n                      and\n                      <jats:styled-content style=\"fixed-case\">BW<\/jats:styled-content>\n                      and have been hypothesized to comprise a high\u2010risk population for asthma. Many previous studies have not accounted for potential confounders or mediators.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>\n                      To investigate the association between twinship and childhood asthma or early life wheeze and identify potential mediators, such as\n                      <jats:styled-content style=\"fixed-case\">GA<\/jats:styled-content>\n                      \/\n                      <jats:styled-content style=\"fixed-case\">BW<\/jats:styled-content>\n                      .\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      The study population consisted of two cohorts including all children born in Sweden from 1 January 1993 to 1 June 2001 (\n                      <jats:italic>n\u00a0<\/jats:italic>\n                      =\n                      <jats:italic>\u00a0<\/jats:italic>\n                      756\u00a0363 singletons,\n                      <jats:italic>n<\/jats:italic>\n                      \u00a0=\u00a022\u00a0478 twins) and 1 July 2005 to 31 December 2009 (\n                      <jats:italic>n<\/jats:italic>\n                      \u00a0=\u00a0456\u00a0239 singletons,\n                      <jats:italic>n<\/jats:italic>\n                      \u00a0=\u00a012\u00a0872 twins). Asthma was defined using validated register\u2010based outcomes of diagnosis or medication. The data were analysed using logistic (older cohort) and Cox regression (younger cohort). Adjusted models incorporated potential confounding or mediating factors including gestational age and birthweight.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      In the younger cohort, the crude hazard ratio (\n                      <jats:styled-content style=\"fixed-case\">HR<\/jats:styled-content>\n                      ) of asthma medication after 1.5\u00a0years of age was 1.12 (95%\n                      <jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>\n                      1.01\u20131.23), and fully adjusted\n                      <jats:styled-content style=\"fixed-case\">HR<\/jats:styled-content>\n                      was 0.80, 95%\n                      <jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>\n                      0.72\u20130.89. Crude\n                      <jats:styled-content style=\"fixed-case\">HR<\/jats:styled-content>\n                      of asthma diagnosis in the same age group was 1.14 (95%\n                      <jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>\n                      0.99\u20131.30), fully adjusted 0.78 (0.68\u20130.98). Adjusted analyses in the older group yielded similar results.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      Twins were at significantly higher unadjusted risk of asthma or early life wheeze compared to singletons in the younger, but not in the older cohort. Associations attenuated following adjustment for\n                      <jats:styled-content style=\"fixed-case\">GA<\/jats:styled-content>\n                      \/\n                      <jats:styled-content style=\"fixed-case\">BW<\/jats:styled-content>\n                      , suggesting that\n                      <jats:styled-content style=\"fixed-case\">GA<\/jats:styled-content>\n                      \/\n                      <jats:styled-content style=\"fixed-case\">BW<\/jats:styled-content>\n                      mediates the effect of twinship on asthma risk. After adjustments, twins were at lower risk of asthma outcomes, possibly due to unmeasured confounding.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/cea.12547","type":"journal-article","created":{"date-parts":[[2015,4,2]],"date-time":"2015-04-02T18:26:29Z","timestamp":1427999189000},"page":"1328-1336","source":"Crossref","is-referenced-by-count":25,"title":["Twins' risk of childhood asthma mediated by gestational age and birthweight"],"prefix":"10.1111","volume":"45","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8759-765X","authenticated-orcid":false,"given":"V.","family":"Ullemar","sequence":"first","affiliation":[{"name":"Department of Medical Epidemiology and Biostatistics Karolinska Institutet Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C.","family":"Lundholm","sequence":"additional","affiliation":[{"name":"Department of Medical Epidemiology and Biostatistics Karolinska Institutet Stockholm 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