How old is a baby?

Infancy refers to the period from birth to one year old. During this period, children's growth and development are relatively fast, and it can even be considered the fastest development stage in their lives. During this time, the baby has already shown certain characteristics in terms of weight, height, chest circumference and brain development. Below, we will introduce the characteristics and nutritional principles of infants in detail.

1. How old is a baby?

Infants are children under 1 year old. Babies grow and develop particularly rapidly at this stage, which is the most rapid growth and development stage in a person's life. Their weight is approximately 9,000 to 10,000 grams.

Babies born at full term already have good sucking and swallowing functions, and have thick fat pads on their cheeks that help with sucking activities, but premature babies have poorer abilities. Sucking is a complex natural reflex. Serious illness can affect this reflex, making sucking weak and powerless.

2. Characteristics of infants

① The body weight can reach three times that at birth, which is about 9,000 to 10,000 grams.

② The height is about 50 cm at birth, and generally increases by 3 to 3.5 cm per month, 10 to 12 cm at 4 months, and can reach about 1.5 times the height at birth at 1 year old.

③The head circumference is about 34 cm at birth, increases by 8 to 10 cm in the first six months, and 2 to 4 cm in the second six months, reaching an average of 46 cm at one year old. The growth rate slows down afterwards, reaching about 56 to 58 cm in adults.

④ The chest circumference is 1 to 2 cm smaller than the head circumference at birth. By the end of 4 months, the chest circumference is basically the same as the head circumference.

⑤ The baby's brain is still in a period of rapid development for a period of time after birth, and the number of brain nerve cells continues to increase. It needs sufficient, balanced and reasonable support of nutrients (especially high-quality protein), so the demand for calories, protein and other nutrients is particularly strong.

3. Nutritional principles for infants

Since vitamin D cannot enter breast milk through the mammary glands, breastfed babies should supplement with vitamin D or get more sun exposure after 2 weeks of birth to prevent rickets. Long-term excessive intake of vitamin D can cause toxic reactions, so the recommended intake is 10 mg per day.

The iron stored in the baby's body is gradually consumed as the baby develops, and the iron content in breast milk is low. Iron-fortified baby cereal can be used as the first weaning food. The baby can also eat formula milk with added lactoferrin to prevent iron deficiency anemia.

Given the infants' needs for protein and calcium, formula milk should be used as a supplement to breast milk for energy, protein, calcium and other nutrients.

Weaning food should avoid containing too much salt or seasoning, and it is best to keep it original to reduce the burden on the baby's kidneys.