Mode of delivery may seriously affect omics studies using umbilical cord blood and amniotic fluid.

There is a general lack of awareness regarding how the mode of delivery can significantly influence the omics composition of biological samples such as umbilical cord blood and amniotic fluid. To address this, we analyzed the impact of delivery mode on proteomic and metabolomic profiles in a cohort of 40 healthy pregnant women without complications, including 16 who had vaginal delivery (VD), 16 who underwent elective cesarean delivery by maternal request (CS), and 8 who had intrapartum cesarean section (Intra_CS). Using label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) for proteomic and untargeted metabolomic analyses, we compared amniotic fluid and cord blood samples across delivery modes. The amniotic fluid proteomic and metabolomic profiles of CS women exhibited clear separation from those of VD individuals, whereas only the proteomic profiles of the Intra_CS group differed when compared to the CS group. In cord blood, metabolomic profiles differed between CS and VD women, but proteomic profiles showed no separation. These findings highlight the significant impact of delivery mode on omics profiles, particularly amniotic fluid proteomics and metabolomics, and cord blood metabolomics. Larger studies are needed to validate these findings and expand their generalizability to broader populations.