Whenever you have an inappropriate elimination problem in a cat, the first thing to do is go to the vet. It’s possible that TC’s spraying has nothing to do with your wife’s pregnancy and everything to do with a urinary tract infection.
Otherwise, male cats usually spray for one of two reasons: advertising for interested females, and marking territory. I would guess that you are making changes in your household due the upcoming new arrival - maybe buying baby furniture? Rearranging things? Schedule changes, more people visiting? Sounds like TC is feeling insecure and marking his territory (I don’t know about the hormonal changes it your wife, but hey, you never know. Cats are peculiar creatures.)
Your vet may be able to help by prescribing something like Prozac for TC to help him deal with the stress. Of course, if he is reacting like this to the changes going on NOW, he may be worse once the baby arrives.
Do you have some way of creating a ‘safe place’ for him? Some place that is HIS, where he can go hide out and not be disturbed? I don’t know what your space considerations are, but something like an empty closet that you can put his litter box, food, and water, maybe a shelf or two to lounge on and a box or something he can ‘hide’ in. Leave the door cracked enough that he can come and go as he pleases, but otherwise leave his ‘space’ alone except for tending to the necessary stuff.
If he has a safe place to retreat where he won’t be disturbed he may feel more secure and quit marking everything as ‘his’.
Too many freaks, not enough circuses.