As far as pregnant camping goes, you can't do much better than FW. The bathhouses are straight luxury compared to most campgrounds. Last time we tent camped at FW it was early October, and I was also pregnant! I put a good fan on a suitcase next to my airbed and had it blow straight at me, and I was fine.
DO make sure your reservation is for an actual site. I wouldn't recommend the primitive tent area. My favorite loop is "Big Bear", the path behind the bathhouse leads right to the evening campfire and outdoor movies.

DO rent a golf cart for getting around. The place is HUGE! If you plan to get one from FW, reserve it well in advance.
DO arrive early and ask for a site close to the bathhouse at check-in.
DO pack snacks. Late night food is harder to come by at FW than at the resorts. Make sure you are prepared for off-hours cravings.
DON'T trust the weather reports. Make sure you have ponchos with you at all times, and bring a LARGE tarp (bigger than your tent) in case it rains, you can tie it up over your tent.
DON'T forget to plug in your golf cart.
DON'T over-schedule your days. Park hopping while pregnant is tough. Allow time each day to relax, dip in the pool, enjoy a boat ride to Wilderness Lodge, or stroll around Downtown Disney.
It rained bad during our final tent experience and we were not prepared, so we got flooded. Hubby and I ended up squeezing on to the floor of my parent's RV, and we bought a pop-up almost as soon as we got home. Other than that, I didn't have any issues.
I am now pregnant with baby number two. Will be 32 weeks on our next trip to FW in November. So, let me know how it goes!
