Top-ranked England have won a record 25 tests in a row and are favourites to win the tournament, which starts in Auckland on October 8th.
"The women’s game will be loss making for some years to come and therefore we have to make challenging decisions around what we can invest in and what will provide the best results and return for the team," the RFU said.
"The Red Roses' wider management support group has recently been expanded to include investment in additional physios, rehab therapists, performance coaches, a nutritionist and a full-time psychologist.
"From a performance perspective the team management has chosen to invest in these areas as well as having two weeks in the country before the first game rather than flying in business," it added.
The players were due to leave London on Friday but will not start full training until September 29th.
British media reported the players were under instruction not to post photographs on social media from their journey because they were not flying with official airline partner British Airways.
"As our airline partner British Airways does not currently fly directly to New Zealand, the team will be travelling to and from the World Cup with an alternative carrier," the RFU said.
