Floribert Nava, 45, pleaded guilty Thursday to carjacking for the March 22, 2013, incident, The Press of Atlantic City, N.J., reported.
Investigators said that on the day of the incident, Nava used a fake gun to force the 17-year-old girl, whose name was not reported, to drive her from Wildwood, N.J., to Philadelphia.
The victim had recently given her newborn up for adoption and Nava, an acquaintance of the victim, believed she should have been given the baby.
During the drive, the victim crashed her vehicle into a police car, jumped out of the vehicle and told officers the passenger in the vehicle had a gun and had kidnapped her earlier in the day.
Nava was arrested and charged with kidnapping, carjacking, terroristic threats and other charges. All but the carjacking charges against her were dropped as part of a plea agreement.