Cat birth problems

My friend has a registered cat, which had a healthy litter of kittens.  Then she was bred to a stray and that litter all died at birth.  Now she has bred her to a new male.  My question:  Could she have contacted something from the stray that would cause the stillbirths?  Could she give it to the new male, and might he pass it on to another cat?

[Vance2335]

Wrong form, this is the STD form.