If it is happening with more than one doe, then you need to change the set-up of your maternity ward, as Picco says. Something is stressing or frightening your mommas. It's terribly hard to avoid looking at the new arrivals, but they really should be left totally alone. Also try to keep them away from loud noises (TV, dogs barking, etc.).
Mini rexes are known to be very good moms, so the problem should solve itself with a little rearranging of their environment.
Good luck!