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Defining preterm delivery – the epidemiology of clinical presentation

Authors

  • K.E. Pickett,

    1. Department of Health Studies, University of Chicago, USA
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  • B. Abrams,

    1. Division of Public Health Biology and Epidemiology, School of Public Health, University of California, Berkeley, and, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, USA
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  • S. Selvin

    1. Division of Public Health Biology and Epidemiology and Division of Biostatistics, School of Public Health, University of California, Berkeley, USA
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Dr. Kate E. Pickett Department of Health Studies, University of Chicago, 5841 South Maryland Ave, MC 2007, Chicago, IL 60637, USA.E-mail: kpickett@health.bsd.uchicago.edu

Abstract

It is possible that preterm delivery is not a single entity but a cluster of conditions with different aetiologies that ultimately result in the delivery of an infant before 37 completed weeks of gestation. Whereas some researchers have reported aetiological heterogeneity, others have found no differences between subtypes or have disputed the desirability and utility of classifying preterm birth into subtypes. This study explores the relationship of maternal risk factors to type of preterm delivery in a cohort of over 7000 black and white women delivering singleton infants at the University of California, San Francisco’s Moffitt Hospital between 1980 and 1990. Although the magnitude of the effect of individual risk factors differed between preterm delivery subtypes, the set of risk factors significantly associated with both categories of spontaneous preterm delivery was identical, while that associated with medically indicated preterm births was different. This study indicates that whereas the distinction between spontaneous preterm deliveries and those that are medically indicated seems valid, distinguishing between types of spontaneous preterm births may not lead to useful aetiological inferences.

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