The woman was believed to be pregnant at the time of shooting, but police now say she was not.
The shooting occurred at 12:55 p.m. at the intersection of 10th and Green Streets in Philadelphia's poplar section.
Police were able to apprehend a man on the 800 block of North 16th Street. A weapon was recovered while taking the man into custody.
The victim's name has not been released.
Police are investigating.