Placentas were disected, halved, and flash-frozen in OCT. Frozen placentas were trimmed to ~7X7 mm squares representing similar regions of interest and 10 μm tissue sections were prepared using a cryostat and placed onto Visium capture areas. Sequencing libraries were prepared using Visium Spatial Gene Expression Slides (10x Genomics) and an 18 minute tissue permeabilization time according to the manufacturer's recommended protocol for fresh frozen tissue (CG000239 Rev C).