Breastfed Babies: Weight Gain & Growth Patterns

Weight gain patterns differ for breastfed and formula-fed babies. Understanding the differences can help prepare you for success at the breast.

Baby breastfeeding

Did you know that breastfed and formula-fed babies have different growth patterns? Studies show that between the ages of three and 12 months, the average weight of breastfed babies is slightly lower than that of formula-fed babies. Breastfed babies also tend to be leaner and take less milk volume per feeding than their formula-fed counterparts since breast milk is more nutritionally dense. 

Despite these differences, growth standard charts remain the same for breastfed and formula-fed babies. But don’t let that scare you. If you’re exclusively breastfeeding, there are certain weight gain patterns you can look for to make sure your tot is getting all the nutrition needed at the breast.

Below we go over the normal weight ranges for breastfed infants over the first year as well as how to read and understand CDC and WHO growth charts.


How much weight should a breastfed baby gain?

According to the latest World Health Organization (WHO) Child Growth Standards, the average breastfed baby doubles its birth weight by 3–4 months. By the first birthday, the average breastfed baby will weigh about 2.5–3 times its birth weight.

Between 0-4 months, breastfed babies should gain an average of 5–7 ounces (170 grams) per week, which breaks down to about 1 ounce per day. Between 4–6 months, that average weight gain changes to about 4–5 ounces (113-142 grams) per week and then to 2–4 ounces per week (57-113 grams) between 6–12 months when solids are introduced.


Baby weight loss after birth

All newborns lose some weight at first, but exclusively breastfed babies lose more weight than those who are formula-fed. In the first three to five days after birth, a 5–7% weight loss is normal for an exclusively breastfed baby. Babies lose fluid and clear out the meconium in their gut; both of these factors contribute to weight loss.

And in these first few days, mothers produce small amounts of colostrum, which is sufficient to meet the baby’s needs as long as the baby is feeding well at the breast. If, however, a newborn loses more than 7% of birth weight in those first five days, the American Academy of Pediatrics recommends getting yourself and your tot evaluated by a healthcare provider for breastfeeding issues.

Exclusively breastfed babies should be at or above their birth weight by 10 to 14 days post delivery. If your baby is sick or premature and has lost extra weight in the early days, it may take longer to regain birth weight. If the baby does not regain birth weight within two weeks, contact a board-certified lactation consultant to make sure that you’re producing enough milk and your baby is taking it in.


Understanding growth charts for breastfed babies         

The American Academy of Pediatrics’ policy statement Breastfeeding and the Use of Human Milk states that “Infant growth should be monitored with the World Health Organization (WHO) Growth Curve Standards to avoid mislabeling infants as underweight or failing to thrive.” The WHO growth charts describe how healthy, breastfed children should grow under the best possible environmental and health conditions.

Growth charts are used to compare weight, height and head circumference against children of the same age. So if a baby is in the 50th percentile for weight on the WHO charts, it means that half of healthy babies of the same age are lighter and half are heavier. If a baby is in the 20th percentile for height, then 80% of babies of the same age are taller and 20% are shorter. A baby in the 5th percentile can be just as healthy as a baby in the 95th percentile.

When doctors use growth charts, they look for steady and proportional growth. However, these charts are only one piece of information and should be evaluated along with other factors, including:

  • Is baby meeting developmental milestones?
  • Is baby gaining consistently, even if not on a curve?
  • What size are the baby’s parents?
  • Is baby showing other signs of adequate milk intake (such as wet and dirty diapers, signs of satiety after feedings)?

If you’re concerned about your baby’s weight gain patterns or your baby’s growth, or you just want to make sure everything is on track, we recommend speaking to your doctor and lactation consultant.


The Tot’s breastfeeding gear & resources

If you breastfeed your baby, we recommend checking out our collection of nursing gear, which includes breast pumps and accessories as well as nursing pillows and covers.

We also encourage you to explore our breastfeeding resources, including these popular articles:

The information on this site is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment.