Are abdominal exercises safe during pregnancy? Yes the exercises are safe if done in the safe manner like sit ups and crunches in the first half of the pregnancy. Lying back flatly might cause constriction in the blood vessels so avoid any exercises which requires such position. Abdominal exercises along with other pregnancy exercises helps in getting the better sleep and reduces the discomforts of the pregnancy. The aches and pain of the muscles get settled down by having regular moderate exercise.