Weight loss for newborns: What to expect at birth

Your newborn’s weight

Your baby’s birth weight is the best single indicator of overall health. As soon as your baby is born, their weight will be checked. While all newborns are born at different weights, the average weight ranges between 5 pounds, 8 ounces, and 8 pounds, 13 ounces. Babies born outside of this average weight range aren't necessarily unhealthy or experiencing abnormal growth, but they may require extra medical attention.

A newborn baby's weight depends on factors including the baby's health, the length of the pregnancy, the mother's health and nutrition during pregnancy, and when the baby was born. Additional factors that can influence your baby's weight are:

• Genetics
• Whether it's a single or multiple birth
• Birth order
• Gender

Weight gain in infants

Babies grow rapidly during their first year of life. Here's how your pediatrician will track your baby's growth:

Weight

Babies typically gain about 1 ounce per day in the first few months, slowing to 0.71 ounces per day by month four. By six months, weight gain further decreases to about 0.35 ounces or less per day.

Height

From birth to 6 months, babies grow approximately 1 inch per month. Between 7 and 12 months, babies grow about half an inch each month.

Head circumference

Your pediatrician will measure your baby's head circumference to monitor brain growth. In the first month, a baby's head circumference increases by about 1 inch and then by 0.4 inches each subsequent month.

There’s no need to worry about your baby’s weight if they are eating well, comfortable during feedings, have regular wet diapers, and seem satisfied afterward. However, if your baby appears uncomfortable or hungry after feeding, check in with your pediatrician or lactation expert about a weight check. Weight checks will provide more information on your baby’s weight gain.

Understanding infant growth charts

During well-check visits, your pediatrician will likely provide information about your baby's growth based on an infant growth chart. This chart tracks your baby's head circumference, weight and length, and gender.

At each well-visit, your pediatrician will track your baby's measurements and input them into a growth chart to compare their growth patterns with other babies. If your child falls into a higher percentile, they are larger than average. If they fall into a lower percentile, they are smaller than average. For example, if your child is in the 20th percentile for weight, it means they weigh more than 20% of kids their age and less than 80%.

Pediatricians use two charts: one by the World Health Organization (WHO) for babies under age 2 and another by the Center for Disease Control (CDC) for children aged 2 and up. The CDC growth chart specifically reflects the growth patterns of American children using data collected since 1977. More recently, the WHO growth chart includes additional factors that may affect growth like racial and ethnic background, body mass index (BMI), premature birth, and accounts for differences in breastfed and formula-fed babies.

As babies grow and develop, they typically follow a consistent growth curve. For example, a child in the 5th percentile will likely continue growing along the 5th percentile over time. Weight changes only become a concern if a child experiences a sudden and significant drop or gain across multiple percentiles.  

Newborn weight loss

It's normal for newborns to lose weight in the first few days after birth. In fact, healthy newborns typically lose 7% to 10% of their birth weight during that time. After a few days, babies usually begin to regain this weight and return to their birth weight within the first two weeks after birth.

If you're experiencing difficulties with breastfeeding, latching, or have questions about breast milk or infant formula, be proactive and ask for help to ensure your baby is well-fed and growing. Contact your local or Summer Health lactation consultant for additional guidance and support.