{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T20:32:50Z","timestamp":1776457970877,"version":"3.51.2"},"reference-count":48,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2022,8,11]],"date-time":"2022-08-11T00:00:00Z","timestamp":1660176000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Intl J Gynecology &amp; Obste"],"published-print":{"date-parts":[[2023,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>To illustrate the difference between exposure effects and population attributable effects.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We examined the effect of mid\u2010pregnancy short cervical length (&lt;25\u2009mm) on preterm birth using data from a prospective cohort of pregnant women in Lusaka, Zambia. Preterm birth was live birth or stillbirth before 37\u2009weeks of pregnancy. For estimation, we used multivariable regression and parametric g\u2010computation.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Among 1409 women included in the analysis, short cervix was rare (2.4%); 13.6% of births were preterm. Exposure effect estimates were large (marginal risk ratio 2.86, 95% confidence interval [CI] 1.80\u20134.54), indicating that the preterm birth risk was substantially higher among women with a short cervix compared with women without a short cervix. However, the population attributable effect estimates were close to the null (risk ratio 1.06, 95% CI 1.02\u20131.10), indicating that an intervention to counteract the impact of short cervix on preterm birth would have minimal effect on the population risk of preterm birth.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Although authors often refer to \u201cthe\u201d effect, there are actually different types of effects, as we have illustrated here. In planning research, it is important to consider which effect to estimate to ensure that the estimate aligns with the research objective.<\/jats:p><\/jats:sec>","DOI":"10.1002\/ijgo.14372","type":"journal-article","created":{"date-parts":[[2022,7,28]],"date-time":"2022-07-28T09:42:16Z","timestamp":1659001336000},"page":"842-849","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Different effects for different questions: An illustration using short cervix and the risk of preterm birth"],"prefix":"10.1002","volume":"160","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2049-6918","authenticated-orcid":false,"given":"Rachael K.","family":"Ross","sequence":"first","affiliation":[{"name":"Department of Epidemiology, Gillings School of Global Public Health University of North Carolina at Chapel Hill  Chapel Hill North Carolina USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephen R.","family":"Cole","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Gillings School of Global Public Health University of North Carolina at Chapel Hill  Chapel Hill North Carolina USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daniel","family":"Westreich","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Gillings School of Global Public Health University of North Carolina at Chapel Hill  Chapel Hill North Carolina USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jessie K.","family":"Edwards","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Gillings School of Global Public Health University of North Carolina at Chapel Hill  Chapel Hill North Carolina USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Patrick","family":"Musonda","sequence":"additional","affiliation":[{"name":"Department of Epidemiology and Biostatistics, School of Public Health University of Zambia  Lusaka Zambia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bellington","family":"Vwalika","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, School of Medicine University of Zambia  Lusaka Zambia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Margaret P.","family":"Kasaro","sequence":"additional","affiliation":[{"name":"University of North Carolina Global Projects Zambia  Lusaka Zambia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joan T.","family":"Price","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, School of Medicine University of Zambia  Lusaka Zambia"},{"name":"University of North Carolina Global Projects Zambia  Lusaka Zambia"},{"name":"Department of Obstetrics and Gynecology, School of Medicine University of North Carolina at Chapel Hill  Chapel Hill North Carolina USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeffrey S. 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