Witness Kareema Cross also said she saw three babies move limbs and a fourth make a sound.
But in defense questioning, she said she saw babies move after their necks had been cut. Prosecutors say Gosnell and his staff killed babies that way after they were born alive.
The defense argues that any movement seen was a postmortem reflex.
Gosnell's lawyer will ask the judge Monday to dismiss the eight murder counts for lack of evidence.