Transcriptome analysis reveals key genes and pathways associated with piglet fetal mummification

China has the largest pork consumption worldwide. However, the high incidence of piglet fetal mummification (3%-5%) is an important factor that causes the slow improvement of pig reproductive capacity, and the genetic mechanism is still unclear. This study aimed to identify candidate genes associated with piglet fetal mummification. RNA-seq technology was used to compare transcriptome profiling of blood from healthy and mummified piglets at different stages of pregnancy (35, 56, 77, and 98 days). A total of 137-420 differentially expressed genes (DEGs) were detected at each stage. Seven DEGs were significantly differentially expressed at various stages. IL-9R, TLR8, ABLIM3, FSH-α, ASCC1, PRKCZ, and GCK may play important roles in the course of piglet fetal mummification. The differential genes we identified between the groups were mainly enriched in immune and inflammation regulation, while others were mainly enriched in reproduction. Considering the function of candidate genes, IL-9R and TLR8 were suggested as the most promising candidate genes involved in mummified piglet traits. We speculate that during pregnancy, it may be the combined effects of the above-mentioned inflammation, immune response, and reproduction-related signaling pathways that affect the occurrence of mummified piglets and further affect pig reproduction.