Total RNA enriched for small RNAs was extracted from placenta-derived exosomes using the miRNeasy Mini Kit (Qiagen, Hilden, Germany) according to the manufacturer's instructions. RNA concentration and purity were assessed by spectrophotometry, and RNA quality and small RNA integrity were evaluated using an Agilent Bioanalyzer or an equivalent platform. Small RNA libraries were constructed following the manufacturer's protocol for miRNA sequencing. Briefly, 3′ and 5′ adapters were ligated to small RNAs, followed by reverse transcription and PCR amplification to generate cDNA libraries enriched for miRNAs. Size selection of library fragments corresponding to mature miRNA inserts was performed using gel- or bead-based purification. The final libraries were quantified, quality-controlled, and sequenced on an Illumina platform.