Hello XXXXXXXXXX,
I would be most concerned about a possible intestinal parasite.
When animals (and people) are pregnant, the hormones that are secreted have an influence on the immune system. (Essentially down regulating the immune system so that the body doesn't respond to the fetus / feti.)
This allows for latent infections to worsen.
The best thing to do is have a fecal sample evaluated by your veterinarian and make sure that she or he knows that your cat is pregnant when considering treatment options.
Now is not the time to get a broad spectrum de-wormer without knowing the affects and which parasite is being treated.
Your veterinarian should be able to help you relatively inexpensively.
I hope this helps!
As always, if you have further questions or concerns, please don't hesitate to ask them using the "reply" function.
Thank you,
Dr. Schillig
Cat Veterinarian
Dr. Schillig has been practicing veterinary medicine for over ten years.