A man also lost consciousness during the Mission: Space attraction at EPCOT.
The ride vehicles used for the safari can be quite bumpy, which likely resulted in the induced labor.
That ride provides significant g-forces and actually has a second version of the attraction for guests who want to experience a lower stress version of the ride.
In addition to the heart attack, Walt Disney World’s quarterly injury report (via WESH) also mentions that a woman went into labor after going on the Kilimanjaro Safari ride at Disney’s Animal Kingdom in April.