from what I have read this is not totally abnormal.  but happens at times.   I feed my gliders OHPW.  they suggest preg. females get it with 1/2 cup of wamboroo mixed in the recipe instead of 1/4 cup to help mom with nursing and all the nutrients she needs.  so a DOUBLE portion.  ALSO the version of this made in  
america called critterlove has a breeders version. 
    So a substantial increase in nourishment is called for preg mommies.  but again since this is not so unusual to have happen even an increase in food doesnt guarantee a change in outcome.   Having a happy home with toys, running wheel and large cage I personally believe would help.