Chikoo is lovely in pregnancy, it gives energy and is easy on the stomach. We always had it as an evening snack at home. Just one or two is enough since it is sweet, and if you have sugar issues check with your doctor.
Just a gentle note, chikoo is on the sweeter side so go easy if you have any sugar concern. I had GD and my doc limited the sweet fruits for me. For a normal pregnancy a small one is fine.