Fetus-Placenta-Newborn
Risk factors for sudden intrauterine unexplained death: Epidemiologic characteristics of singleton cases in Oslo, Norway, 1986-1995,☆☆

https://doi.org/10.1067/mob.2001.110697Get rights and content

Abstract

Objective: The epidemiologic characteristics of unexplained stillbirths are largely unknown or unreliable. We define sudden intrauterine unexplained death as a death that occurs antepartum and results in a stillbirth for which there is no explanation despite postmortem examinations, and we present risk factors for this type of stillbirth in singleton gestations. Study Design: Singleton antepartum stillbirths (n = 291) and live births (n = 582) in Oslo were included and compared with national data (n = 2025 and n = 575,572, respectively). Explained stillbirths (n = 165) and live births in Oslo served as controls for the cases of sudden intrauterine unexplained death (n = 76) in multiple logistic regression analyses. Results: One fourth of stillbirths remain unexplained. The risk of sudden intrauterine unexplained death (1/1000) increased with gestational age, high maternal age, high cigarette use, low education, and overweight or obesity. Primiparity and previous stillbirths or spontaneous abortions were not associated with sudden intrauterine unexplained death. Conclusions: Risk factors for sudden intrauterine unexplained death are identifiable by basic antenatal care. Adding unexplored stillbirths to the unexplained ones conceals several risk factors and underlines the necessity of a definition that includes thorough postmortem examinations. (Am J Obstet Gynecol 2001;184:694-702.)

Section snippets

Material and methods

The registration period comprised January 1, 1986– December 31, 1995. The material is presented in Fig 1.

. Flow chart showing quantification of material (Norway, upper section; Oslo, lower section ), with preliminary sources of data (dotted boxes ) and final sources of data submitted to analysis (solid boxes). Asterisk, Nonvalidated data from the Medical Birth Registry of Norway; SIUD, Sudden intrauterine unexplained death.

Data were collected from the Medical Birth Registry of Norway on all

Results

One fourth of all stillbirths remained unexplained despite postmortem examinations. The collected data presented in Tables II to V demonstrate several characteristics of sudden intrauterine unexplained death that differ from well-known risk factors for antepartum stillbirths in general.

Comment

The findings of risk factors for sudden unexplained intrauterine death in this study, some in conflict with earlier reports and some in contrast to other causes of antepartum stillbirths, underline the necessity of a definition of sudden intrauterine unexplained death that includes thorough postmortem examinations. Including the unexplored, borderline cases of sudden intrauterine unexplained death, as most previous studies have done, can conceal detectable risk factors or create confounding

Acknowledgements

We thank the Medical Birth Registry of Norway and the staff at Aker University Hospital, Ullevål University Hospital, and The National Hospital for invaluable help in providing the material for this study. J. Frederik Frøen, MD, is a fellow with the Norwegian Women’s Public Health Association.

References (20)

There are more references available in the full text version of this article.

Cited by (0)

Supported by the Norwegian Women’s Public Health Association.

☆☆

Reprint requests: J. Frederik Frøen, MD, Department of Pediatric Research, The National Hospital, University of Oslo, Pilestredet 32, N-0027 Oslo, Norway.

View full text