Trends in the causes of stillbirths over 20 years in Southern Japan.

BACKGROUND

This study aimed to determine the temporal trend in the causes of stillbirths over a period of two decades using a regional perinatal database in order to facilitate the development of perinatal strategies to prevent stillbirths in Japan.

METHODS

This was a population-based retrospective study. Cases of perinatal death and neurological damage were reported by perinatal centers and primary birth clinics, followed by their peer review and audit, and final registration in the database. Data for stillbirths, defined as fetal death at ≥ 22 weeks of gestation between January 1, 2001, and December 31, 2020, were extracted from the database. Causes of stillbirths were reclassified according to the ReCoDe system. Temporal trends in the causes of stillbirths per 1,000 births and proportion of the causes were evaluated using the Cochran-Armitage test.

RESULTS

Over the 20 years, in the study region, a total of 205,025 were delivered at ≥ 22 weeks of gestation, and 569 were stillborn (2.8 per 1,000 births). The most common cause of stillbirth was "no relevant condition identified" in 39.5% cases, followed by "abruption" in 12.3%, "lethal congenital anomaly" in 9.5%, and "umbilical cord, other" in 5.8%. The trends in stillbirths caused by "fetal growth restriction," "abruption," "asphyxia," and "no relevant condition identified" significantly decreased. However, no change in trend due to "lethal congenital anomaly" was seen. The stillbirth trend caused by "cord, other" significantly increased. The proportion of stillbirths related to unidentified causes remained unchanged.

CONCLUSIONS

Over the 20-year period, the rate of stillbirths caused by abruption, fetal growth restriction, and asphyxia, which can be reduced by early detection and intervention, decreased. The incidence of stillbirths caused by cord constriction increased. Investigations to prevent cord-accident stillbirths would be required to further reduce stillbirths in the study region. Establishment of algorithms that allow the identification of the causes of stillbirths would be crucial to reduce instances of stillbirths due to unidentified causes.