Prototypical cytokines and chemokines associated with influenza (53), including interferons (IFNs), tumor necrosis factor (TNF) α, interleukin (IL)−6, and CCL2 were upregulated throughout infection in the lungs but not the spleens of IAV-infected dams (Fig. 1D; Tables S2 and S3). Here, CCL2 is linked to infection.