Mako Vunipola will start at loose-head prop for England in Saturday's RBS 6 Nations match against Italy at the Stadio Olimpico.
Vunipola replaces Joe Marler, who is with his partner ahead of the imminent birth of their first child.
Matt Mullan (London Wasps) comes on to the replacements' bench.
England Head Coach Stuart Lancaster said: "It is important that Joe is with his partner at this exciting time. Family must always come first and everyone in the squad wishes them well.
"We have prepared for being without Joe and we have no doubt Mako will slot straight in and perform, as will Matt Mullan from the bench should he get an opportunity."
England team to play Italy: M Brown, J Nowell, L Burrell, B Twelvetrees, J May, O Farrell, D Care, M Vunipola, D Hartley, D Wilson, J Launchbury, C Lawes, T Wood, C Robshaw, B Morgan
Replacements: T Youngs, H Thomas, D Attwood, T Johnson, L Dickson, G Ford, M Tuilagi
Live television coverage of the RBS 6 Nations from 12:00 on Saturday 5 March (12:30 Italy v England, 14:45 Wales v Scotland, 17:00 France v Ireland) on RTÉ Two and RTE.ie (Ireland only). Live radio coverage of France v Ireland on Saturday Sport (14:00) on RTÉ Radio 1 and RTÉ.ie (Worldwide).