Physical Development

What color are your baby's eyes? Believe it or not, you may not know for sure until sometime around her first birthday. Most Caucasian babies are born with slate gray or dark blue eyes, while most Asian and Black babies have dark brown eyes. Although the dark color is permanent, light eyes will continue to gain pigment for at least three to six months, and in some cases, much longer. So those gray eyes may stay gray--or they may turn blue, hazel, or brown.

Hair undergoes similar changes in color and texture in the first six months. Babies of color who were born with soft, curly hair may end up with a wirier, wavier 'do. Many Caucasian babies lose their hair altogether, then grow new tresses with a completely different texture, and sometimes, color. There doesn't seem to be any rhyme or reason to infant hair color, so don't be alarmed if your baby turns from brunette to blonde (or vice versa)--it's perfectly normal. She may also develop a bald spot on the back of her head from all the time she spends lying on her back; this will clear up by itself in time.

Social Development

At 4 months, your little one is much better at interacting with siblings than she was a month ago. She is quickly developing attachments to family members. As a result, your older children will probably start to enjoy the baby more, responding with affection as she smiles and coos just for them. To nurture this fledgling relationship, give your older ones as much one-on-one time as you can, perhaps hiring a sitter to watch the baby a few hours a week so you can schedule a special activity. Respect older children's boundaries, as well--don't let the baby wreak havoc in their bedrooms or destroy their toys.

Intellectual Development

Your baby now recognizes all the sounds that make up her native language, and is ready to start producing some herself. She'll start with vowels, repeating them over and over for as long as 15 minutes in a variety of pitches and tones. At the same time, she'll watch the mouths and faces of the people around her, absorbing the ways in which different sounds combine into syllables, words, and sentences.

Over the next few months, your baby's babbling will become more and more complex as she learns to incorporate the rhythms she hears. She may come up with a variety of sounds all at once, or experiment with one for several days before moving on to the next. Help her along by repeating sounds back to her as you introduce simple words such "apple", "up", "eye", and "it."

Note: The information above offers general guidelines, but all babies develop differently, and few hit their milestones precisely when the conventional wisdom says they should. If your child was born prematurely, you may want to use your due date as a baseline for following baby's development.