General Obstetrics and Gynecology: ObstetricsMaternal-fetal conditions necessitating a medical intervention resulting in preterm birth
Section snippets
Material and methods
We utilized the state of Missouri's live birth data files from 1989 to 1997 for analysis. These data correspond to births abstracted from birth certificates of live-born infants.17, 18 Gestational age, reported in completed weeks, was largely based on menstrual dating. When the menstrual estimate of gestational age was inconsistent with the birth weight (eg, extremely low birth weight at term), a clinical estimate of gestational age, also contained on the vital records, was used instead, in
Results
The preterm birth rate at less than 35 weeks was 4.6% (n = 31,238). The distribution of maternal characteristics among near-term/term births and preterm births at less than 35 weeks is shown in Table I. Proportions of women aged less than 20 years, women with less than 12 years of schooling, Black race/ethnicity, single and those that smoked were higher in the preterm than near-term/term births.
Among all preterm births at less than 35 weeks, 23.5% (n = 7347) were medically indicated. The
Comment
The concept of separating preterm births on the basis of their underlying clinical subtypes to understand etiologies is not new.10, 11, 12, 23, 24 It has long been recognized that preterm birth is a heterogeneous end point with two major clinical subtypes, namely spontaneous and medically indicated preterm birth.3, 10, 25, 26, 27, 28 Much of the attention has been focused on its origins as well as the prediction and prevention of spontaneous preterm birth. However, 20% to 35% of all preterm
Acknowledgments
We thank the staff of the Missouri Vital Statistics Department for making the data files available to us. We appreciate the thoughtful comments from Darios Getahun, MD, MPH; Wendy Kinzler, MD; Yinka Oyelese, MD; and Hamisu Salihu, MD, PhD, on an earlier draft of the manuscript.
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Supported in part through a grant (R01-HD038902) from the National Institutes of Health (to C.V.A.).