Mako Vunipola will start at loosehead prop for England in Saturday's clash with Italy in Rome due to Joe Marler's unavailability.
Marler withdrew from the team on Thursday with his partner expecting the couple's first child.
Vunipola's place on the replacements bench will be taken by Matt Mullan.
An England statement said Marler was staying at home with his partner ahead of the "imminent" birth of their first child.
With British and Irish Lions stalwart Alex Corbisiero still sidelined with a knee injury, fourth-choice prop Mullan now finds himself in the matchday 23.
"It is important that Joe is with his partner at this exciting time," said England coach Stuart Lancaster.
"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 should he get an opportunity.
"Matt played in the autumn internationals. There's no problem with him, he's been involved right throughout the campaign. He's a good player to come on."
England (revised): 15 Mike Brown, 14 Jack Nowell, 13 Luther Burrell, 12 Billy Twelvetrees, 11 Jonny May, 10 Owen Farrell, 9 Danny Care, 8 Ben Morgan, 7 Chris Robshaw, 6 Tom Wood, 5 Courtney Lawes, 4 Joe Launchbury, 3 David Wilson, 2 Dylan Hartley, 1 Mako Vunipola.
Replacements: 16 Tom Youngs, 17 Matt Mullan, 18 Henry Thomas, 19 David Attwood, 20 Tom Johnson, 21 Lee Dickson, 22 George Ford, 23 Manu Tuilagi.
Date: Saturday, February 15
Venue: Stadio Olimpico, Rome
Kickoff: 14:30 (local, 13:30 GMT)
Referee: Pascal GauzÃ¨re (France)
Assistant Referees: Nigel Owens (Wales), Leighton Hodges (Wales)
TMO: Simon McDowell (Ireland)