Calcium tablets are usually needed in the fourth month of pregnancy. In a normal pregnancy, the fetus in the womb begins to calcify its bones and teeth in the fourth month; calcification accelerates in the eighth month of pregnancy and continues until full term, when all the milk teeth are formed, so extra calcium supplements are needed in the fourth month of pregnancy. The calcium she gets from food may not be enough to meet the needs of the fetus’ bones and teeth, so the rest of the calcium needs to be taken from calcium-containing foods and high-quality calcium tablets. After the fourth month of pregnancy, the daily requirement of calcium for pregnant women increases to 1000mg-1200mg, so during the fourth month of pregnancy, you can eat moderately more calcium-containing foods and calcium tablets to get a certain amount of calcium from them.