IFNA1 and infection: However, in analyzing ~17 months of breeding records from WT, Ifnar1−/−, Ifnlr1−/−, and Ifnar1−/−Ifnlr1−/− mice in our colony (>275 litters from >40 breeder cages), we found no significant difference in litter size between the lines, supporting the idea that IFN signaling during pregnancy is not detrimental outside an infection or other inflammatory context.