The couple, Nachman and Raizy Glauber, both 21, were in a cab heading to a hospital early Saturday when they were hit by a black BMW, the New York Post reported.
The Glaubers were pronounced dead at the hospitals to which they were transported. Doctors at Bellevue Hospital performed a Cesarean section on Raizy Glauber, who was seven months pregnant with the couple's first child.
However, the child died early Monday from injuries sustained in the crash said Isaac Abraham, a community leader in Brooklyn and a neighbor of the Glaubers.
The driver of the cab sustained slight injuries, for which he was treated at a hospital and released.
Police are still searching for the driver and a passenger of the BMW, who fled the scene of the crash.
Detectives said they believe they know the names of the suspects and have shown their pictures to possible witnesses.
Meanwhile, Takia Walker, a 29-year-old Bronx resident who had co-signed the BMW's lease, has been charged with insurance fraud.
Walker allegedly obtained the car under false pretenses and then allowed someone else to drive it without notifying the insurance company.