Despite media reports that Cameron's spokeswoman has already gone on maternity leave, PRWeek understands that she is not set to do so until the end of the year.
Downing Street is believed to be working on a plan for Gabby Bertin's replacement, which comes after the loss of Andy Coulson and Steve Hilton from the Prime Minister's team of trusted advisers.
One well-placed source said: 'The truth is that they haven't made a call on what happens next. Obviously, the hole she will create is impossible to fill.
'Someone who knows the PM and his wife and family as intimately as Gabby is hard to find.'
It is understood that no new Downing Street comms appointments are planned, although some new faces are expected in Cameron's policy unit, where vacancies are not yet thought to have been filled.
Meanwhile, as the Prime Minister drew up his plans for his new Cabinet, industry sources told PRWeek that several special advisers were fine-tuning their CVs in preparation for the reshuffle.
Several special advisers are thought to have renewed contact with their former employers, many of which are PR and lobbying firms.