Breastfeeding A to Z

Three Weeks Old

These are some things to know about your baby, around the time they are three weeks old:

Brain–your baby’s brain grows rapidly during infancy.  Human milk is designed to optimize brain growth. (1)

Mouth–your baby cries to signal a need, which may be for food, comfort, warmth, their mother’s presence, pain, illness or fear.  When you or other caregivers promptly respond to your baby’s cries, a secure and trusting relationship begins to develop. (1)

Taste–flavors from foods you eat flavor your breastmilk.  This helps babies become accustomed to the taste of foods in their native diet, before they can eat solid foods. (1)(2)

Stomach–breastmilk is more easily digested than formula, it takes a greater volume of formula than breastmilk to produce the same growth in your baby.  Breastmilk is better utilized than formula in your baby’s system. (1)

Bloodstream–immunity from disease is related to the amount of breastmilk your baby takes in. (1)  Ideally your baby will be exclusively breastfed, but even if they are given formula, the greater the amount of breastmilk they receive, the greater the immunity they receive. (1)


  1. Lawrence, RA, Lawrence, RM, Breastfeeding: A Guide for the Medical Professional, 7th edition, Maryland Heights, MO, Elsevier Mosby, 2011, pp 7, 215, 216-17, 272, 324.
  2. Mohrbacher, N, Stock, J, La Leche League International The Breastfeeding Answer Book, 3rd revised edition, Schaumburg, IL, La Leche League International, Jan 2003, p 131.