Police said a 25-year-old man, named Aaron McKenzie, was charged Sunday with killing both Fauvrelle and her son, and with possession of an offensive weapon.
Fauvrelle was approximately eight months pregnant when she was attacked in her bedroom at Thornton Heath, south London, while the rest of her family was at home, Britain's Press Association (PA) news agency reported.
Police previously arrested two other men on suspicion of murder, but a 37-year-old man was released with no further action and a 29-year-old was released on bail.
McKenzie, who has been charged with murder and manslaughter is due to appear in court on Monday.
Few weekends pass without reports of knife violence, and flowers laid on London street corners serve as near-daily reminders of its results.