A newborn’s stomach is very small and gradually grows as the baby develops. Its capacity also increases as the baby consumes breast milk, infant formula, and eventually solid foods.
During the first few days of life, the baby’s stomach grows quickly. It can hold approximately 7 mL of milk on the first day, 22 mL by the third day, and around 45 mL by the seventh day.
After the first year, a baby’s stomach continues to grow in proportion to body weight. Its estimated capacity is 30 to 40 mL per kilogram, meaning an 18-month-old baby who weighs 10 kg may have a stomach capacity of approximately 300 to 400 mL.
Newborn stomach size by age
A baby’s stomach size varies with age and the amount of food or milk the baby can consume:
A baby’s stomach becomes larger as the baby grows, allowing the baby to consume more milk during each feeding.
When to start breastfeeding
Breastfeeding should begin as soon as possible, preferably within the first hour after delivery. Skin-to-skin contact, such as placing the baby on the mother’s chest in the delivery room, helps stimulate breast milk production.
How breastfeeding should be done
Because a newborn’s stomach is small, the baby should receive small amounts of breast milk or infant formula several times throughout the day.
It is normal for a newborn to need 10 to 12 feedings per day at first because the stomach cannot hold a large amount of milk.
Regardless of stomach size, exclusive breastfeeding is recommended for approximately the first 6 months of life. Breastfeeding may continue until age 2 or beyond for as long as the mother and child wish, with the baby generally being fed on demand whenever hunger cues are present.
A pediatrician may recommend infant formula when the mother cannot breastfeed or when breastfeeding is contraindicated, such as because of certain contagious illnesses or the use of specific medications.
When to introduce solid foods
Solid foods should generally be introduced at around 6 months of age, whether the baby is breastfed or fed infant formula.
A baby’s first purees can be made with fresh fruits that are mashed or finely grated, such as apples, pears, bananas, and papayas.
Starting at around 7 months, more substantial purees can be served at lunch and dinner. These meals may contain rice, pasta, cassava, sweet potatoes, chicken, beef, carrots, chayote squash, and zucchini, which should be mashed or prepared in a texture appropriate for the baby’s developmental stage to reduce the risk of choking.