Growth and Your 1- to 3-Month-Old

Like they did as newborns, most babies grow quickly in weight and length during the first few months of life.

How Much Do Babies This Age Grow?

After losing some of the birth weight (up to 10%) during the first few days of life, your baby should have regained that weight and then some, gaining at least 2/3 ounce (18.9 grams) per day.

As a 1- to 3-month-old, your baby will likely continue to grow at a similar rate, while also gaining 1 to 1.5 inches (2.54 to 3.81 centimeters) in length per month. These are just averages. Your baby may grow somewhat faster or slower, and is likely to experience growth spurts along with other times of slower growth.

Your pediatrician will measure your baby's weight, length, and head circumference and track your baby's growth pattern on a standardized growth chart (there are different charts for boys and girls). Generally, whether your baby is large, small, or medium-sized, as long as your child's growth pattern stays consistent over time, chances are excellent that he or she is doing fine.

If your baby is born

How many feedings a day your baby gets. A breast-fed baby may feed 8 to 12 times in a 24-hour period; bottle-fed babies usually eat less frequently, perhaps every 3 to 4 hours.

How much your baby eats at each feeding. A baby generally nurses for at least 10 minutes, should be heard to swallow, and should seem satisfied when he or she is done. Bottle-fed babies eat about 3 to 4 ounces (88.72 to 118.29 milliliters) a feeding during the first month, with an extra ounce (29.57 milliliters) per feeding for each additional month.

How often your baby urinates. Babies should have at least 4 to 6 wet diapers a day.

How many bowel movements your baby has each day, and their volume and consistency. Breast-fed babies' stools should be soft and slightly runny. The stools of formula-fed babies tend to be a little firmer, but should not be hard or formed. Frequency of bowel movements depends on age and type of feeding.

Most of the time, a baby's growth will simply be tracked over the next few months during routine well-baby visits. But if your pediatrician is concerned about your baby's growth, he or she will want to see your baby more frequently. Breastfeeding mothers may benefit from meeting with a lactation (breast-feeding) counselor who can make suggestions to improve technique.

You may have heard the term "failure to thrive," which describes a baby who is gaining weight more slowly than he or she should but does not get at the cause. Sometimes, there may be a medical reason for slow growth, which would require further evaluation.

Call your baby's doctor if your baby is not feeding well or if you have concerns about your baby's growth or development. Call the doctor immediately if your infant is vomiting every feeding, not wetting his or her diapers, has a fever, or seems listless or unresponsive.

What's Next?

In most cases, breast milk or formula is all a baby needs for the first 6 months of life, but some doctors may recommend introducing iron-fortified rice cereal at 4 months. Talk with your baby's doctor before starting any solids or changing formula.

Reviewed by: Steven Dowshen, MD