{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T05:17:37Z","timestamp":1790227057748,"version":"4.1.0"},"reference-count":22,"publisher":"Wiley","issue":"12","license":[{"start":{"date-parts":[[2016,5,13]],"date-time":"2016-05-13T00:00:00Z","timestamp":1463097600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"name":"March of Dimes Prematurity Research Center at Stanford University"},{"name":"Stanford Child Health Research Institute and the Stanford Clinical and Translational Science Award","award":["UL1 TR001085"],"award-info":[{"award-number":["UL1 TR001085"]}]}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["BJOG"],"published-print":{"date-parts":[[2016,11]]},"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>To investigate the distribution of known factors for preterm birth (<jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>) by severity of maternal underweight; to investigate the risk\u2010adjusted relation between severity of underweight and <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>, and to assess whether the relation differed by gestational age.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>Retrospective cohort study.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>State of California, <jats:styled-content style=\"fixed-case\">USA<\/jats:styled-content>.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Maternally linked hospital and birth certificate records of 950\u00a0356 California deliveries in 2007\u20132010 were analysed. Singleton live births of women whose prepregnancy body mass index (<jats:styled-content style=\"fixed-case\">BMI<\/jats:styled-content>) was underweight (&lt;18.5\u00a0kg\/m<jats:sup>2<\/jats:sup>) or normal (18.50\u201324.99\u00a0kg\/m<jats:sup>2<\/jats:sup>) were analysed. Underweight <jats:styled-content style=\"fixed-case\">BMI<\/jats:styled-content> was further categorised as: severe (&lt;16.00), moderate (16.00\u201316.99) or mild (17.00\u201318.49). <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content> was grouped as 22\u201327, 28\u201331, 32\u201336 or &lt;37\u00a0weeks (compared with 37\u201341\u00a0weeks). Adjusted multivariable Poisson regression modeling was used to estimate relative risk for <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main outcome measures<\/jats:title><jats:p>Risk of <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>About 72\u00a0686 (7.6%) women were underweight. Increasing severity of underweight was associated with increasing percent <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>: 7.8% (<jats:italic>n\u00a0<\/jats:italic>=<jats:italic>\u00a0<\/jats:italic>4421) in mild, 9.0% (<jats:italic>n\u00a0<\/jats:italic>=<jats:italic>\u00a0<\/jats:italic>1001) in moderate and 10.2% (475) in severe underweight. The adjusted relative risk of <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content> also significantly increased: adjusted relative risk (<jats:styled-content style=\"fixed-case\">aRR<\/jats:styled-content>)<jats:italic>\u00a0<\/jats:italic>=<jats:italic>\u00a0<\/jats:italic>1.22 (95% <jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content> 1.19\u20131.26) in mild, <jats:styled-content style=\"fixed-case\">aRR<\/jats:styled-content><jats:italic>\u00a0<\/jats:italic>=<jats:italic>\u00a0<\/jats:italic>1.41 (95% <jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content> 1.32\u20131.50) in moderate and <jats:styled-content style=\"fixed-case\">aRR<\/jats:styled-content><jats:italic>\u00a0<\/jats:italic>=<jats:italic>\u00a0<\/jats:italic>1.61 (95% <jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content> 1.47\u20131.76) in severe underweight. These findings were similar in spontaneous <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>, medically indicated <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content>, and the gestational age groupings.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Increasing severity of maternal prepregnancy underweight <jats:styled-content style=\"fixed-case\">BMI<\/jats:styled-content> was associated with increasing risk\u2010adjusted <jats:styled-content style=\"fixed-case\">PTB<\/jats:styled-content> at &lt;37\u00a0weeks. This increasing risk was of similar magnitude in spontaneous and medically indicated births and in preterm delivery at 28\u201331 and at 32\u201336\u00a0weeks of gestation.<\/jats:p><\/jats:sec><jats:sec><jats:title>Tweetable abstract<\/jats:title><jats:p>Increasing severity of maternal underweight <jats:styled-content style=\"fixed-case\">BMI<\/jats:styled-content> was associated with increasing risk of preterm birth.<\/jats:p><\/jats:sec>","DOI":"10.1111\/1471-0528.14027","type":"journal-article","created":{"date-parts":[[2016,5,13]],"date-time":"2016-05-13T08:09:01Z","timestamp":1463126941000},"page":"2001-2007","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":71,"title":["Women's prepregnancy underweight as a risk factor for preterm birth: a retrospective study"],"prefix":"10.1111","volume":"123","author":[{"given":"AI","family":"Girsen","sequence":"first","affiliation":[{"name":"Department of Obstetrics &amp; Gynecology Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"JA","family":"Mayo","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"SL","family":"Carmichael","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"CS","family":"Phibbs","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"},{"name":"Health Economics Resource Center Veterans Affairs Palo Alto Healthcare System Menlo Park CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"BZ","family":"Shachar","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"DK","family":"Stevenson","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"DJ","family":"Lyell","sequence":"additional","affiliation":[{"name":"Department of Obstetrics &amp; Gynecology Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"GM","family":"Shaw","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"JB","family":"Gould","sequence":"additional","affiliation":[{"name":"Department of Pediatrics Division of Neonatal and Developmental Medicine Stanford University School of Medicine Stanford CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"name":"the March of Dimes Prematurity Research Center at Stanford University School of Medicine","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2016,5,13]]},"reference":[{"key":"e_1_2_6_2_1","unstructured":"March of Dimes.White paper on preterm birth: The global and regional toll 2009."},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(08)60136-1"},{"key":"e_1_2_6_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2004.09.021"},{"key":"e_1_2_6_5_1","doi-asserted-by":"publisher","DOI":"10.1111\/ppe.12125"},{"key":"e_1_2_6_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2013.12.011"},{"key":"e_1_2_6_7_1","doi-asserted-by":"publisher","DOI":"10.1111\/apa.12616"},{"key":"e_1_2_6_8_1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2013.6295"},{"key":"e_1_2_6_9_1","unstructured":"HarrisG.Study says pregnant women in india are gravely underweight. 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