Objective To compare the rates and aetiologies of stillbirth over the past 50 years.

Study design We reviewed all autopsy reports for stillbirths occurring between 1989 and 2009 at the McGill University Health Centre to determine the pathological aetiology of stillbirths. We also reviewed maternal characteristics. We compared our results with a previous study published in 1992 on aetiologies of stillbirth from 1961 to 1988 at the same institution.

Results From among the 79 410 births between 1989 and 2009, 217 stillbirths were included in our study. The mean maternal age was 31.05 (±5.8) years. In 28.1% of cases, there was a history of subfertility. The mean gestational age at diagnosis was 32.69 (±5.58) weeks, with a birthweight of 1888 (±1084) g. The main causes of stillbirth were unknown (26.7%), placental factors (19.8%) and abruptio placentae (12.9%). Other causes included haematogenous or ascending infection (10.6%), fetal malformations (8.3%), maternal hypertension (3.2%), intrauterine growth restriction (2.8%), diabetes (1.8%) and intrapartum asphyxia (1.4%). Other fetal causes were found in 12.4% of cases.

Conclusions Owing to detailed pathological examination of most stillbirth cases over the past five decades at our tertiary obstetrical centre, we could study the trends in the aetiology of stillbirths in a cohort of more than 150 000 births. In 50 years, the rate of stillbirth has decreased from 115 to 32 cases/10 000 births from the 1960s to 2000s, which represents a reduction of 72%. Stillbirth from unknown cause remains the most common contributor, with 40% of these cases occurring in late pregnancy.