I'd like to back up what Opus wrote.
Changes like this in kitty's box habits is a sign that something else is going on.
Teia (our soon to be 14 year old rescue kitty) was peeing and pooping in the walk in closet where she'd taken up residence. This was (we found) in reaction to one of our other kitties (Chessie) that Teia does not like using her litter pan.
Used the enzymatic cleaner (Urine Be Gone in this case) on both WIC carpet and litter box, put up a baby gate so Chessie can not invead Teia's space, no more problem.
So, please look for an underlying reason kitty has changed her habits. A vet visit is in order, I agree.
meant to add, she can sense your hormonal change but thats NOT the reason she is doing this...theres another problem going on.
heres more reading..
http://healthypets.mercola.com/sites/healthypets/archive/2011/06/16/tracking-down-the-cause-of-your-cats-bad-bathroom-habits.aspx
congrats to you:)
first of all you need to find out why the cat is doing this, its not b/c you are pregnant, there is a reason...I'll send you a site that list possible reasons...could well be a medical issue, how old is she? has she had a recent urinalysis to rule out a bladder infection or crystals??? this is very common esp wiht older kitties. usually they are trying to tell yu something is wrong/or it HURTS......
copy and paste the following site to answer many of your questions.....you can also read there abt the homemade recipe for cleaning soiled areas..don't know if this works, but I do know some commercial products do...such as Urine Erase, Frizzon On, Natures Miracle...buy from a good pet shop, they have to contain the enzyme that removes the scent from the cats perspective remember their noses are much more sensitive than ours, they can still detect scents that we cannot...and all traces have to be removed or the cat will continue to use this spot.
so you need to find out the CAUSE than remove scent from all areas the cat has used...good luck, please don't get rid of her...so many are given up for this reason and it usually just takes some detective work to solve...yes she can sense your hormonal change:)
http://www.catsofaustralia.com/kitty-litter-box-problems.htm