The 23-year-old suffered an interior cruciate ligament injury in January while on international duty with the Black Stars at the 2017 Africa Cup of Nations in Gabon.
Rahman was linked with a return to Bundesliga side Schalke for another season-long loan in July but Chelsea preferred to keep him at the Cobham Training Centre to continue his recovery.
“We are hoping that he [Baba Rahman] would be back before the year ends,” Conte said ahead of Chelsea's game against Watford on Saturday.
“He is an option [for us] and we are even short of men but we have to take it carefully because his situation was complicated,” he added.
Chelsea will be without N'Golo Kante, Danny Drinkwater, Victor Moses and Tiemoue Bakayoko, leaving them thin on the ground in midfield while Alvaro Morata is still out following a hamstring injury picked up against Manchester City. David Luiz will have to pass a late fitness test.