Burpees are the fundamental cross-fit move but its traditional form is not safe to be done during your 2nd or 3rd trimester. You can try a modified version as explained below.
Stand in front of an elevated surface such as a box, tall bench, or a wall. Keep your toes pointed outwards.
Drop a squat by keeping your weight on your heels and allowing the knees to bow a bit.
Do a pushup against the elevated surface when you are squatting. This makes one repetition.
Perform five sets of ten to twelve reps.