Overview of sample processing, storage, and analysis. Placenta and decidua specimens were obtained from 9 women by 8 mm punch biopsy. For each specimen, 3 aliquots were placed in RNAlater, and 2 aliquots were flash frozen by immersion in liquid nitrogen. RNA extraction from matched sample aliquots was performed immediately (baseline), after 1 month of storage, and after 8–10 months of storage. All stored samples were kept at −80°C. RNA was subsequently used for analysis of RIN values and housekeeping gene expression.