What are the effect on babies born after a mom has had ketamine abuse?

None: Ketamine will leave the body's system after a few hours and should have no effect, especially in the dose used to supplement either a spinal or epidural or IV sedation anesthetic. The ketamine was probably used so that the patient would not feel pain or stop moving excessively.

Few studies: There have been few studies of this particular question, but you're right that ketamine can be abused (not only used in anesthesiology). It's called Special K on the street. One report i did find showed the infant was small for gestational age, had remarkable hypotonia, and poor reflex response. www.ncbi.nlm.nih.gov/pubmed/20951358 other reports mentioned learning disabilities in older kids.