Police say the 36-year-old woman was near the intersection of West Rock Hill Road and Bryn Mawr Avenue in Lower Merion shortly before 3 p.m. when a car hit two parked vehicles.
Five pedestrians, including the mother-to-be, were struck.
The four other pedestrians were hospitalized for their injuries, while the expecting mother did not survive.
"That's very upsetting because I'm sure they were just enjoying the evening or visiting friends and then that happens," noted Andrew Hanks from Bala Cynwyd.
Neighbors who spoke with Action News say that the intersection is incredibly dangerous.
There are no sidewalks and only one stop sign despite a lot of foot traffic in the area, especially with two schools nearby that release students in the afternoon.
"It's a little bit of a blind intersection. You have to poke your head out and look both directions and see which way you're going and be sure that you're not getting sideswiped by somebody," said Hanks.
Police have not identified the pregnant woman who was killed.
Officers say this incident was not a hit-and-run, but no information was released on the driver involved.
Authorities also said there was a physical altercation after the crash.
When Action News asked investigators whether charges would be filed, officials said the crash was still under investigation.