Comparison of the utility of components of perinatal autopsy in early gestation/small foetuses

Modern perinatal autopsy encompasses multiple components (fetal examination, placental examination, imaging, genetics, and microbiological studies) which may have varying utility within different contexts. In Australia, stillbirth is often defined as death of a baby from 20 completed weeks of gestation or of at least 400 grams birthweight. As part of a retrospective audit of all cases referred to Austin Health for perinatal autopsy from 2021–2024 inclusive, the relative contribution of different postmortem investigations were compared in babies delivered prior to 20 weeks gestation and those delivered at or above 20 weeks gestation but weighing less than 400g (excluding cases of termination for fetal anomalies). In 89 autopsies of babies delivered before 20 weeks gestation, significant findings were most frequently deduced from placental examination (53.9% of cases) followed by microbiology (8.9%), genetics (6.7%), imaging (3.4%), and foetal examination (2.2%). In an additional 25 autopsies of babies delivered after 20 weeks and weighing less than 400g, there were no significant findings on foetal examination, imaging, or microbiology. Genetic and placental pathology contributed to 4.0% and 36.0% of cases respectively. These findings suggest that in this cohort, placental histopathology is the most crucial component of perinatal autopsy, while foetal examination is the least contributory.