If racing and that level of effort is NORMAL for you, which it sounds like it is, then it should be fine--but you should consult your doctor first. I raced and continued my normal training up to 5 months pregnant. Then I had to back off the racing and continue with less intense workouts. I actually did an 8-hour adventure race in 14 degrees, in the middle of a blizzard when I was just over 5 months pregnant. I had to mountain bike 10 miles in several inches of snow on single track. Canoe 4 miles (in a blizzard!!!! sitting in an aluminum canoe--BRRRRR!!!!). And trail run/hike for 5ish miles. And I'm not near as tough as it sounds.

CX Racing is doable. Your baby will never be in a safer place than in your womb

My advice is to pay very close attention to your body, stay well hydrated and do not get overheated. Don't do anything you aren't comfortable doing.

Good luck and congratulations!!!!