As a parent you give your children a good start in life—you nurture, protect, and guide them. Learn about developmental milestones, including emotional and social development, for babies from birth to 1 year of age. There are many things you can do to help your baby stay safe and healthy. It’s important to understand exactly what happens during the newborn, infant and toddler stage of life and learn what milestones they should be hitting. Let's explore each of these stages in a bit more detail. The meaning of INFANT is a child in the first period of life. How to use infant in a sentence. Different words are used for a baby at different stages of growth. These words are not used in the same way by everyone. For example, the word infant may be used until a baby can walk, or only until the baby is one year old. A baby from birth to about 3 months old is sometimes called a newborn. In common terminology, a baby is the very young offspring of adult human beings, while infant (from Latin īnfāns 'baby, child', literally 'unspeaking') [1] is a formal or specialised synonym. The terms may also be used to refer to juveniles of other organisms. Breastfeeding, also called nursing, is the process of feeding human breast milk to an infant, either directly from the breast or by expressing (pumping out) the milk from the breast and bottle-feeding it to the infant. CDC's Milestone Tracker helps you track your child's milestones from age 2 months to 5 years. Provides information on child development and milestones. The term infant usually refers to a baby from birth to around 1 year of age. You may also use the term “baby” during this time or “newborn” for little ones up to around 3 months of age. Infant development: Birth to 3 months Infant development begins at birth. Consider major infant development milestones from birth to 3 months — and know what to do when something's not right. Merriam-Webster defines an infant as a child in the first period of life but doesn't give any age specifics. It describes a baby as an extremely young child. .