The vast majority of pregnant women without special circumstances are first advised to start taking calcium tablets after 12 weeks of pregnancy. This is because during the first trimester of pregnancy, calcium tablets may cause gastrointestinal reactions due to relatively severe early pregnancy reactions. So even if you take calcium tablets, they will be vomited out and not effective. Secondly, it is recommended to consider taking calcium tablets after the third trimester of pregnancy, and must be taken under the guidance of a doctor, not in excess, so as not to cause clinical adverse effects. Again, it is recommended to eat more calcium-containing foods in the diet, such as more sesame seeds or more milk, or more nuts in the clinic, all of which are helpful for calcium supplementation. It is also recommended to take frequent sunbathing or walks in daily life to promote gastrointestinal peristalsis and increase appetite, and to take in calcium from food.