Physical Development

All babies cry--it's their primary form of communication. But 10 to 20 percent of infants are subject to prolonged crying fits--otherwise known as colic--that usually start in the early evening.

Although the word "colic" strikes fear into every parent's heart, it's not a dangerous condition--just frustrating and exhausting. It's heartbreaking to watch your little one cry for two hours or more every evening, and even harder to realize that you can't make the discomfort go away. Colic generally starts at about 3 weeks of age, peaks at 6 weeks, and subsides after two to three months. Possible causes range from underfeeding to overfeeding, allergies, constipation, diarrhea, gas, intestinal cramps, and tension, but the bottom line is that no one knows for sure.

Social Development

Your little one learns about the world through interaction--first with you, then with other family members, and later with friends. From the very beginning, she'll be fascinated by your facial expressions, and comforted when you sing or talk to her. To provide visual stimulation and aid sensory development, make faces that correspond to your emotions: Smile when you say her name, wrinkle your nose when you change her diaper, frown at loud noises from outside. She'll love it when you act silly, so wiggle your ears, stick out your tongue, and sing funny songs. (Don't worry if you can't carry a tune in a bucket--she'll be delighted all the same.)

In the early months, your face will be your baby's favorite plaything. But she'll also respond positively to other stimuli. Newborns like simple, high-contrast objects, such as black-and-white checkerboard patterns and faces drawn with simple features. A mobile over her crib or bassinet will provide hours of amusement.

Intellectual Development

In many ways, your newborn's world begins and ends with you. She doesn't yet have a sense of herself as a separate person, but she associates your presence with comfort, pleasure, and nourishment. She identifies you in three main ways: through your appearance, voice, and smell. When she hears your voice, her eyes will move in its direction, and she will try to follow your face (which she recognizes from the time she is 36 hours old) if you move it close to hers. She will also respond to your scent, and will show a distinct preference for both you and the milk you produce--babies given a choice between breast pads soaked with their mother's milk and the milk of another woman consistently choose their own.

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.