Pregnant women infected with pandemic influenza A(H1N1)pdm09 virus showed differential immune response correlated with disease severity.

•The expression of the M gene was the same in all groups of pregnant women.•No differences were observed in MCP-1, RANTES and IP-10 expression in all groups.•Increased expression of IL-8 and TGF-α in infected pregnant women.•IL-6 showed higher expression in pregnant women who died.•IFN-β and TGF-β expression were lower in those pregnant women who died.