Autopsy-Based Growth Charts May under-Detect Fetal Growth Restriction at Autopsy

Abstract

Background: Accurate identification of fetal growth restriction in fetal autopsy is critical for assessing causes of death. We examined the impact of using a chart derived from ultrasound measurements of healthy fetuses (World Health Organization fetal growth chart) versus a chart commonly used by pathologists (Archie et al.) derived from fetal autopsy-based populations in diagnosing small-for-gestational-age (SGA) birth in perinatal deaths. Study Design: We examined perinatal deaths that underwent autopsy at BC Women’s Hospital, 2015-2021. Weight centiles were assigned using the ultrasound-based fetal growth chart for birthweight and autopsy-based growth chart for autopsy weight. Results: Among 352 fetuses, 30% were SGA based on the ultrasound-based fetal growth chart versus 17% using the autopsy-based growth chart (p < 0.001). Weight centiles were lower when using the ultrasound-based versus autopsy-based growth chart (median difference of 9 centiles [IQR 2, 20]). Conclusions: Autopsy-based growth charts may under-classify SGA status compared to ultrasound-based fetal growth charts.

Keywords:

• Fetal growth restriction
• small for gestational age
• autopsy-based growth charts
• ultrasound-based growth charts

Acknowledgements

We would like to thank Kelvin Chui for his contributions to data abstraction in support of this project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

MJK received a University of British Columbia Faculty of Medicine Summer Studentship for this research, JL is supported by a Michael Smith BC Health Professional Investigator Award, and JAH is supported by a Canada Research Chair in perinatal population health. These funders did not have any role in the research design or decision to submit the manuscript.