Which brand of calcium tablets is best for pregnant women suffering from calcium deficiency? 1. Causes of calcium deficiency in pregnant women and its impact on the body. Pregnant women need a large amount of calcium in their bodies to support the growth and development of the fetus and to maintain their own bone health. If pregnant women lack calcium, it will lead to symptoms such as osteoporosis, anemia, convulsions, and irregular heartbeat, which are detrimental to the health of both the pregnant woman and the fetus. 2.Which brands are they?