Striker Wood has missed the last two games with a knee problem, while winger Marshall sustained an ankle injury during the Championship defeat to Peterborough on February 9 and missed the home FA Cup loss to Huddersfield three days later.
Central defensive duo St Ledger and Whitbread have been out for considerably longer.
Republic of Ireland international St Ledger is back in the frame for the first time since the start of October when he suffered a hamstring injury in Leicester's 2-0 home win over Bristol City.
Whitbread has missed the last nine matches with a calf problem.
Leicester's defeat to Peterborough, combined with them having the weekend off due to Blackburn's involvement in the FA Cup, has seen Nigel Pearson's side fall out of the automatic promotion places and down to fifth in the table.