Placental villous biopsies were collected immediately after delivery and either snap-frozen and stored at -80°C or placed in RNALater solution for 24 h at 4°C prior to storage at -80°C until processing. Frozen biopsies were ground on dry ice, and approximately 20 mg of powdered tissue was homogenized in lysis buffer using QIAshredder columns (QIAGEN, Canada). Frozen RNALater-preserved placenta biopsies were cut on dry ice and thawed directly into lysis buffer in prefilled tubes containing garnet shards and a 6 mm zirconium bead (Benchmark Scientific, USA). Mechanical lysis was performed using a BeadBug homogenizer (Benchmark Scientific, USA), followed by complete homogenization through the QIAshredder columns (QIAGEN, Canada). Total RNA was extracted using the RNeasy Mini kit (QIAGEN, Canada) according to the manufacturer's instructions. RNA purity (OD260/280 ratio ≥ 1.8) and concentration (ng/μL) were determined using a NanoDrop spectrophotometer (Thermo Fisher Scientific, Canada). rRNA-depleted libraries (HMR rRNA depletion) were prepared from 125 ng of total RNA at Génome Québec and sequenced on an Illumina NovaSeq platform (Illumina, USA).