The primary dietary source of calcium during pregnancy is dairy products because they contain highly bioavailable calcium essential for fetal skeletal development and maternal bone health. Dairy products provide a concentrated and easily absorbed form of calcium compared to plant sources, which often contain oxalates and phytates that inhibit calcium absorption. Adequate calcium intake from dairy helps prevent maternal bone demineralization and reduces the risk of hypertensive disorders like preeclampsia. Ensuring sufficient calcium through dairy is therefore critical during pregnancy for both mother and baby.

Reference: Maternal and Child Health Care, Sharma S.K., 2nd Edition.