Objective: To develop and test a new classification system for stillbirths to help improve understanding of the main causes and conditions associated with fetal death.
Design: Population based cohort study.
Setting: West Midlands region.
Subjects: 2625 stillbirths from 1997 to 2003.
Main outcome measures: Categories of death according to conventional classification methods and a newly developed system (ReCoDe, relevant condition at death).
Results: By the conventional Wigglesworth classification, 66.2% of the stillbirths (1738 of 2625) were unexplained. The median gestational age of the unexplained group was 237 days, significantly higher than the stillbirths in the other categories (210 days; P < 0.001). The proportion of stillbirths that were unexplained was high regardless of whether a postmortem examination had been carried out or not (67% and 65%; P = 0.3). By the ReCoDe classification, the most common condition was fetal growth restriction (43.0%), and only 15.2% of stillbirths remained unexplained. ReCoDe identified 57.7% of the Wigglesworth unexplained stillbirths as growth restricted. The size of the category for intrapartum asphyxia was reduced from 11.7% (Wigglesworth) to 3.4% (ReCoDe).
Conclusion: The new ReCoDe classification system reduces the predominance of stillbirths currently categorised as unexplained. Fetal growth restriction is a common antecedent of stillbirth, but its high prevalence is hidden by current classification systems. This finding has profound implications for maternity services, and raises the question whether some hitherto "unexplained" stillbirths may be avoidable.