Your Baby's Growth: 4 Months

Babies this age continue to grow — in size, physical skills, and their ability to interact with the world.

Many of the new skills they're learning will come in handy for eating solid food. In fact, some time over the next few months, your baby may 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 Will My Baby Grow?

By 4 months, many babies have doubled their birth weight. This month, babies gain about 1 to 1¼ pounds (560 grams) and about 0.8 inches (2 centimeters) in length.

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 numbers 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 big enough? 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 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 pee?

The doctor also may ask questions about your baby's health and development. All of these things together will help the doctor decide if your baby is growing at an appropriate rate. The doctor may recommend tests if he or she thinks there may be a 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, advice from the baby's doctor can be useful.

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. For the first year, breast milk or formula should continue to be their main source of nourishment.

It's safe to introduce solid foods at around 6 months for breastfed babies, and between 4 to 6 months for formula-fed babies. When the time is right, start with a single-grain cereal for babies (rice cereal has traditionally been the first food for babies), and then introduce other foods, such as puréed fruits, vegetables, or meats. Your doctor can advise you on how much of each food to give, but pay close attention to your baby's cues that he or she has had enough.

What's Next?

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

Reviewed by: Mary L. Gavin, MD
Date reviewed: December 2014