OverTheRainbow, I would be concerned about a SSM during the 3rd trimester. That's when my marriage began to fall apart. After the baby her body's going to need to recover, and then one or both of you will be sleep-deprived. Not finding time/energy may only get worse, with resentment on top of everything else. My XW wouldn't talk about the issue. I bought conservative lingerie which she refused to wear.
I used to think "exciting" required new acts. I now realize subtle changes can create unique sensations. If you feel she's too conservative for even, say ice and warm oil, consider new positions, angles, beds. Yes, one of my favorite experiences involved a hotel bed with overly-bouncy springs! It's more the spirit of adventure--not, "Is this a good bed?" but "What positions and angles is this bed best for?" It's about a fun journey and being playful together, not just a destination, which of course you can reach alone.
I don't know how long your relationship is. The only relationship where I accepted boring sex was with my XW. In other relationships, it's been exciting 5yrs in. My XGF reports it was exciting 20yrs in. Boring sex is now a dealbreaker for me. It can be kept exciting as long as both parties want it to be exciting.
My SSM wasn't about a lack of romance but about my wife's growing depression. As Steve says, the lack of sex is often an indicator of something else that may be going wrong. Consider that.
