Babies this age continue to bloom — in size, physical skills, and ability to interact with the world. In most cases, this is the age when babies begin to respond to their name, reach for objects, sit alone, and make happy sounds — or show frustration when a new skill proves too hard to master right away.

Many of the new skills they're learning will come in handy for eating solid food. In fact, sometime during this period, your baby will probably get that first taste of food beyond breast milk or formula. Although breastfeeding or formula feeding will continue to be the main source of nourishment, your baby can start to explore different tastes and textures. As long as your baby continues to grow steadily, eating habits shouldn't be a cause for concern.

How Much Do Babies This Age Grow?

By 4 months expect birth weight to have doubled. Babies gain about 1-1¼ pounds (450-560 grams) a month and length also continues to increase greatly, perhaps 2 inches (5 centimeters) during this period. There is no strict rule of thumb about how much a baby should weigh at this stage, but your baby should be growing at steady rate.

Since your child's birth, the doctor has been recording growth in weight, length, and head size (circumference) during your regular well-baby visits. The doctor tracks these figures on standard growth charts. Ask your doctor to show you your baby's growth record. By now, you should begin to see a personal growth curve emerging — expect your child to continue growing along this curve.

Should I Be Concerned?

Is my baby too fat? Too thin? Is my child destined to be tall or short? Parents often worry about growth and may compare a baby with siblings and peers. It's important to remember that kids come in a wide range of shapes and sizes.

Growth depends on many factors, including:

• genes passed on by the parents (kids tend to resemble their parents in height)
• the amount and quality of food a child eats
• overall health
• the functioning of the hormones that control aspects of growth

Based on the growth chart, the doctor can determine whether your child is growing as expected. If at any time you're concerned about your baby's weight or growth in general, discuss your worries with your doctor.

In response to your concerns, the doctor may ask you these questions:

• How many feedings a day does your baby get?
• How much does your baby eat at each feeding?
• How long does a breastfeeding baby nurse at each feeding?
• What else are you feeding your baby?
• How frequent are your baby's bowel movements? What do they look like?
• How often does your baby urinate?

In addition, the doctor may ask questions about your baby's health and development. All of these factors together will help the doctor decide if your baby is growing at an appropriate pace. The doctor may recommend further medical evaluation if he or she thinks there may be an underlying problem that needs to be addressed.

Premature babies may still be behind in size compared with their full-term peers, but they should also be growing steadily at their own rate.

What About the Chubby Baby?

With all the concern about childhood obesity, parents may worry that their baby is getting too fat. A few babies and toddlers are overweight. For these children, professional advice from the baby's doctor can be useful.

But never withhold food from a baby in an attempt to cause weight loss. To grow and develop as they should, babies need proper nutrition, including fat, in their diet.

Make sure the foods your baby eats are nutritious rather than full of "empty" calories. For instance, many babies drink a lot of apple juice, which is high in calories and has little nutritional value. Juice is not recommended for infants younger than than 6 months. After 6 months, 100% fruit juice can be introduced in a sippy cup (limited to 4 ounces, or 120 milliliters, or less a day).

Introduce pureed vegetables and fruits without added sugar and don't give your baby desserts or other sweets that are high in sugar and offer little nutritional value. Also, look for the cues that your baby is full and don't use food to keep your little one quiet or occupied. A crying baby may just be looking for some attention.

If you're concerned about your baby's weight — or even if you're not — encourage activity. For a baby this age, that means plenty of time to move around in a safe space rather than being confined to a carrier, stroller, or other equipment that limits movement.

It also means playing in ways that encourage your baby to develop skills, such as reaching for objects, rolling, and crawling. Some parents take babies this age to organized exercise programs. That's fine if you and the baby both enjoy it, but they're not necessary.

You might also want to look at your own habits. If parents are overweight, have unhealthy eating habits, and get little physical activity, their kids are much more likely to grow up to be overweight.

Your child is growing so fast that before you know it, he or she will be copying what you do. It's never too early to start improving your own habits so you can be a better role model for the ones you love. Besides, being in good shape to run, jump, bike, and actively play with your child can be one of the great joys of being a parent. It's like being a kid again.

What's Next?

Your baby's rapid growth will start to slow down as the first birthday approaches. Expect big changes in the coming months as your infant becomes more mobile.

Reviewed by: Mary L. Gavin, MD
Date reviewed: September 2011