This study addresses the critical gap in epidemiological data on antenatal depression in China, a condition that profoundly impacts maternal and infant health. Conducted as a cross-sectional survey from December 2019 to March 2023, the research enrolled 100,200 pregnant women across 27 hospitals in 11 provinces, municipalities, and autonomous areas. Late-pregnancy depressive symptoms were evaluated using the Edinburgh Postnatal Depression Scale (EPDS). This survey reveals that the overall prevalence of possible depression (EPDS >9) was 25.8%, and probable depression (EPDS >12) was 11.4%, with significant regional variation (highest in North China, lowest in East China). Young maternal age, low education levels, low family income, unemployment, living alone, unmarried/divorced status, unintended pregnancy, multiple pregnancy, insufficient social support, tobacco/alcohol use, and poor sleep quality were identified as risk factors for antenatal depression. Notably, family support, particularly from partners, emerges as a pivotal intervention target for reducing antenatal depression risk.