1.Babies born prematurely and with low birth weight (less than 3 kg) 2.Babies born to mothers with calcium deficiency during pregnancy 3.Babies nursed by mothers with calcium deficiency during breastfeeding 4.Babies with less sun exposure, which is the main cause of vitamin D deficiency. 5.Babies who grow too fast 6.Babies who eat less milk These six types of babies are prone to calcium deficiency and are the key targets for prevention. We check against our own babies to see if any of them belong to the above 6 cases are now discussed specifically. Premature babies are babies born at less than 37 weeks of gestation. Calcium deficiency in women during pregnancy and lactation is manifested as calf cramps, excessive sweating, back pain, and numbness in the hands and feet. In fact, most pregnant women and lactating mothers have different degrees of calcium deficiency. In addition to drinking milk and taking calcium supplements, pregnant women and lactating mothers also need more sunlight. The standard of baby milk quantity: within 4 months: all milk 4 to 6 months: 1 to 2 supplements per day, other milk 6 to 8 months: 600 to 800 ml 9 to 12 months: more than 800 ml More than 1 year old: about 600 ml More than 2 years old: about 500 ml Also note: babies in winter are most likely to be calcium deficient because of insufficient sun exposure or incorrect sun exposure methods.