In the first month of life, babies often catch up and exceed their birth weight. Then they steadily continue to gain weight. A weight loss up to about 10% of birth weight is normal in the first 2 to 3 days after birth. But the baby should have gained this back and be at his or her birth weight by about 2 weeks old. All babies may grow at a different rate. Here is the average for boys and girls up to 1 month old:

• Weight. After the first 2 weeks, should gain about 1 ounce each day.

• Average length at birth:

  • 20 inches for boys

  • 19 3/4 inches for girls

• Average length at 1 month:

  • 21 1/2 inches for boys

  • 21 inches for girls

• Head size. Increases to slightly less than 1 inch more than birth measurement by the end of the first month.

A newborn spends about 16 hours a day sleeping. But the time a baby is awake can be busy. Much of a newborn's movements and activity are reflexes or involuntary. This means the baby does not purposefully make these movements. As the nervous system begins to mature, these reflexes give way to purposeful behaviors.

Reflexes in newborns include:

• Root reflex. This reflex happens when the corner of the baby's mouth is stroked or touched. The baby will turn their head and open their mouth to follow and "root" in the direction of the stroking. The root reflex helps the baby find the breast or bottle.

• Suck reflex. When the roof of the baby's mouth is touched with the breast or bottle nipple, the baby will begin to suck. This reflex does not begin until about the 32nd week of pregnancy. It is not fully developed until about 36 weeks. Premature babies may have a weak or immature sucking ability. That's because they are born before this reflex develops. Babies also have a hand-to-mouth reflex that goes with rooting and sucking. They may suck on their fingers or hands.

• Moro reflex. This is often called a startle reflex. That's because it often happens when a baby is startled by a loud sound or movement. In response to the sound, the baby throws back their head, throws out their arms and legs, and cries. Then the baby pulls their arms and legs back in. Sometimes a baby can be startled by their own cries. That also can trigger this reflex. The Moro reflex lasts until the baby is about 5 to 6 months old.

• Tonic neck reflex. When a baby's head is turned to one side, the arm on that side stretches out. And the opposite arm bends up at the elbow. This is often called the "fencing" position. The tonic neck reflex lasts until the baby is about 6 to 7 months old.

• Grasp reflex. Stroking the palm of a baby's hand causes the baby to close their fingers in a grasp. The grasp reflex lasts only a couple of months. It is stronger in premature babies.

• Babinski reflex. When the bottom of the foot is firmly stroked, the big toe bends back toward the top of the foot and the other toes fan out. This is a normal reflex until the child is about 2 years old.

• Step reflex. This is also called the walking or dance reflex. A baby seems to take steps or dance when held upright with their feet touching a solid surface.

Newborn babies also have many physical characteristics and behaviors that include the following:

• Head sags when lifted up, needs to be supported

• Turns head from side to side when lying on his or her stomach

• Eyes are sometimes uncoordinated, may look cross-eyed

• First fixes eyes on a face or light, then begins to follow a moving object

• Begins to lift head when lying on stomach

• Jerky, erratic movements

• Moves hands to mouth

At this early age, crying is a baby's only form of communication. At first, all of a baby's cries sound the same. But parents soon recognize different types of cries for hunger, discomfort, frustration, tiredness, and even loneliness. Sometimes, a baby's cries can easily be answered with a feeding or a diaper change. Other times, the cause of the crying can be a mystery. The crying stops as quickly as it begins. But whatever the cause, it's important to respond to your baby's cries with a comforting touch and words. This helps your baby learn to trust you and rely on you for love and security. You may also use warmth and rocking movements to comfort your baby.

You may find that your baby responds in many ways, including the following:

• Startles at loud noises

• Looks at faces and pictures with contrasting black and white images

• Gives attention to voices, may turn to a sound

• Hints of a smile, especially during sleep

Young babies need the security of a parent's arms. They understand the reassurance and comfort of your voice, tone, and emotions. The following things can all help your newborn to feel emotionally secure:

• Hold your baby face to face.

• Talk in a soothing tone and let your baby hear your affectionate and friendly voice.

• Sing to your baby.

• Walk with your baby in a sling, carrier, or a stroller.

• Swaddle your baby in a soft blanket to help him or her feel secure and prevent startling by the baby's own movements.

• Rock your baby in a rhythmic, gentle motion.

• Respond quickly to your baby's cries.