Temporal trends in stillbirth in the United States, 1992–2004: a population‐based cohort study. (27th May 2014)

• Record Type: Journal Article
• Authors: Zhang, X; Kramer, MS
• Is Part Of: BJOG. Volume 121:Number 10(2014:Oct.)
• Page Start: 1229
• Page End: 1236
• Publication Date: 2014-05-27
• Subjects: Obstetrics -- Periodicals; Gynecology -- Periodicals; 618
• DOI: 10.1111/1471-0528.12883
• Languages: English
• ISSNs: 1470-0328

Abstract

<abstract abstract-type="main" id="bjo12883-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bjo12883-sec-0001" sec-type="section"> <title>Objective</title> <p>To examine temporal trends in stillbirth and its risk factors in the United States (US), and to assess the contribution of labour induction and caesarean delivery to the stillbirth rate.</p> </sec> <sec id="bjo12883-sec-0002" sec-type="section"> <title>Design</title> <p>Population‐based cohort study based on linked birth‐infant death and fetal death data files from the US National Vital Statistics System.</p> </sec> <sec id="bjo12883-sec-0003" sec-type="section"> <title>Setting</title> <p>Complete data were available for 44 states and the District of Columbia.</p> </sec> <sec id="bjo12883-sec-0004" sec-type="section"> <title>Population or Sample</title> <p>Singleton births from 1992 to 2004.</p> </sec> <sec id="bjo12883-sec-0005" sec-type="section"> <title>Methods</title> <p>We assessed changes in stillbirth rates from 1992–1994 to 2002–2004 before and after adjustment for changes in maternal characteristics including maternal age, education, smoking, and medical risk factors, using Cox regression models. We also carried out an ecological study, using states as the units of analysis, to assess the impact on the stillbirth rate of increasing induction and caesarean delivery. Race‐specific subgroup analyses were performed and included non‐Hispanic Whites and non‐Hispanic Blacks.</p> </sec> <sec id="bjo12883-sec-0006" sec-type="section"> <title>Main outcome measure</title> <p>Stillbirth rate.</p> </sec> <sec id="bjo12883-sec-0007" sec-type="section"> <title>Results</title> <p>The stillbirth rate among non‐Hispanic White singleton births decreased 11.5% from 1992–1994 (5.2 per 1000) to 2002–2004 (4.6 per 1000). After adjustment for maternal risk factors, the hazard ratio (HR) for 2002–2004 was 1.01 (0.99, 1.03) for gestational age (GA) ≤39 weeks, but 0.92 (0.86, 0.99) at 40 or more weeks. The ecologic analysis revealed a nonsignificant negative correlation of −0.17 (−0.44, 0.13) between state‐level changes in stillbirth at GA ≥40 weeks and labour induction. A nonsignificant positive correlation of 0.23 (−0.07, 0.49) was observed between changes in stillbirth at all GAs and caesarean delivery and did not differ at GA ≤39 versus ≥40 weeks. Results were similar among non‐Hispanic Blacks.</p> </sec> <sec id="bjo12883-sec-0008" sec-type="section"> <title>Conclusions</title> <p>Changes in maternal risk factors explained the reduction in stillbirth at GA ≤39 weeks but not at ≥40 weeks. The rise in labour induction and caesarean delivery rates did not explain the reduction in stillbirth ≥40 weeks of gestation.</p> </sec> </abstract>