Newborn weight gain, weight loss, and why it matters

What's the average weight for a newborn?

The average baby weight at birth in the United States is just over 7 pounds (7.18 pounds or 3,255.71 grams, to be very exact).

Here's the breakdown of birthweights among babies born in the United States in 2020:

• 499 grams or less (less than 1 pound 2 ounces): 0.13 percent
• 500 to 999 grams (1 pound 2 ounces to 2 pounds): 0.49 percent
• 1,000 to 1,499 grams (2 pounds 3 ounces to 3 pounds 5 ounces): 0.71 percent
• 1,500 to 1,999 grams (3 pounds 5 ounces to 4 pounds 7 ounces): 1.61 percent
• 2,000 to 2,499 grams (4 pounds 7 ounces to 5 pounds 8 ounces): 5.29 percent
• 2,500 to 2,999 grams (5 pound 8 ounces to 6 pounds 10 ounces): 19.14 percent
• 3,000 to 3,499 grams (6 pounds 10 ounces to 7 pounds 11 ounces): 38.91 percent
• 3,500 to 3,999 grams (7 pounds 11 ounces to 8 pounds 13 ounces): 26.16 percent
• 4,000 to 4,499 grams (8 pounds 13 ounces to 9 pounds 15 ounces) 6.50 percent
• 4,500 to 4,999 grams (9 pounds 15 ounces to 11 pounds): 0.87 percent
• 5,000 grams or more (11 pounds or more): 0.10 percent

Low birth weight is considered less than 2,500 grams (5 pounds, 8 ounces). In 2020, 8.24 percent of babies were born low birth weight, and 1.34 percent were born very low birth weight (less than 1,500 grams, or 3 pounds 4 ounces).

A high birth weight means that a baby weighs 4,000 grams (8 pounds 13 ounces) or more. About 7.5 percent of babies are born with a high birth weight.

A newborn's weight depends on a number of factors, including the parents' size and ethnicity, Mom's health and age, and how much Mom gained during pregnancy. Other factors include the baby's health and gestational age (premature babies are often smaller), whether the baby is a boy or girl, a first baby or later baby, or a singleton or multiple. Being small or large at birth doesn't mean your baby will be small or large later in life.

Why does newborn weight gain matter?

Tracking your newborn's growth in height and weight over time gives your baby's doctor a good sense of your baby's general health.

When a baby doesn't gain weight at a healthy rate, they may be diagnosed with a condition called failure to gain weight (or failure to thrive). This usually happens if they aren't eating well or aren't absorbing or using nutrients properly. It could be due to a feeding problem, a gastrointestinal issue, or some other medical condition.

Healthcare providers will keep a close eye on your baby's weight gain because good nutrition is crucial for your baby's mental and physical development.

While you're still in the hospital, a doctor or nurse will weigh your baby at birth and every 24 hours after birth. Your baby will be weighed again when you come in for your first doctor visits (usually in the first week after you leave the hospital, when your baby is 3 to 5 days old) and at all your baby's well-child visits during the first year. These measurements are recorded on your baby's growth chart.

If your baby is having any health problems, including unexpected weight loss or jaundice, you may have to see the doctor more often in the first few weeks.

What's normal weight loss for a newborn in the first days after birth?

Most healthy, full-term babies lose between 5 and 10 percent of their birth weight in the first days after birth. This can be worrisome if you're not expecting it, but it's perfectly normal.

This early weight loss happens because babies are born with extra fluid that gets eliminated after birth. This weight loss isn't a concern unless a baby loses more than 10 percent of their birth weight.

Your baby needs little food now (their tummy is tiny!), so it might take your little one a couple of weeks to gain the weight back, but within 5 days they'll probably be heading upward on the scale. If your baby loses a lot of weight or is ill or a preemie, it can take longer, perhaps 3 weeks or so.

How much weight will a newborn gain in the first weeks after birth?

Babies usually start to gain weight again 5 to 7 days after birth, and most should be back to (or above) their birth weight by the time they're about 2 weeks old.

In the first month, newborns typically gain about an ounce (30 grams) daily, or a total of 5 to 7 ounces a week. By the end of the first month, most babies will weigh between 1 and 2 pounds above their birth weight. They also grow about 1 to 1.5 inches (2.54 to 3.81 centimeters) in height during this month.

Many factors go into a baby's weight gain in those first weeks of life, including how fast your breast milk comes in (if you're breastfeeding) and how much your baby wants to eat. For example, you may notice your baby wants to eat more often or for longer when they're between 7 and 10 days old, when they're having a growth spurt. (When a baby wants to eat again soon after a full feeding, it's called cluster feeding.)

Look for more growth spurts around 2 to 3 weeks, and at 6 weeks, 3 months, and 6 months. (Although not all babies follow this timeline, and a growth spurt can happen at any time!)

After the first month, a baby typically gains about 3 to 5 ounces a week until 12 months. While breastfed infants may gain more quickly in the first few months, formula-fed babies gain more rapidly after that. Over the course of the first year, healthy breastfed babies tend to gain more slowly than formula-fed infants. By their second year, their weights are typically similar.

How can I tell if my newborn is gaining enough weight?

You may not have a scale suitable for weighing your baby at home. Luckily, counting your baby's dirty diapers is another good way to tell that your baby is doing fine:

• Wet diapers: In the first five days, your newborn may wet only a few diapers each day. After that, expect about 6 to 8 wet diapers a day.
• Poopy diapers: In the first few days, some babies may poop just once daily. After that, expect your baby to poop at least twice a day. (A breastfed baby will have more poopy diapers, say five or more. A formula-fed baby may only have a few.)

It's helpful to track newborn diaper changes in a journal, on BabyCenter's printable baby care log, or with an app on your phone.

In addition, your baby's healthcare provider will be tracking your baby's weight (along with their height and head circumference) at each visit.

Find out more ways to tell if your baby is getting enough breast milk or formula.

What if my baby loses too much weight after birth or isn't gaining enough?

It's a good idea to check in with your baby's healthcare provider if you notice that your baby isn't feeding well or wetting or soiling enough diapers.

Talk with their provider about specific measures you can take, including:

• Regular weighing. You may want to bring your baby to the doctor's office for frequent weighing until they're on track.
• If you're breastfeeding, have your baby empty one breast before offering them the other. This way, they'll get the hindmilk (which is highest in fat) at the end.
• If you're breastfeeding, nurse your baby every two hours during the day. If you're bottle feeding, offer the bottle every three hours. In either case, don't go for more than four hours at night between feedings.
• If you're breastfeeding, work with a lactation consultant to make sure your baby's latch is good and to address any breastfeeding problems. (Sometimes a simple change in position or technique is all that's needed.)
• Avoid giving your baby a pacifier until after they've eaten.

Ask your baby's provider when they'd like you to get in touch between visits. (They may say to call if your baby wets fewer than four diapers in a day, for example, or if your baby starts refusing to eat). Always call with concerns, including any signs of dehydration such as darker, stronger urine or a dry, parched mouth and lips.

Take your baby to the emergency department if they show any signs of serious dehydration, including sunken eyes and sunken fontanels (the soft spots on your baby's head), excessive sleepiness, or extreme fussiness.

When do babies double their birth weight?

Babies typically double their birth weight by about 4 months old. By their first birthday, your baby will probably triple their birth weight!

Along the way, your baby may stop gaining for a short period, or even lose a bit of weight. But over time, the trend of your baby's growth on a curve should be steady. Between visits, let your healthcare provider know if you're concerned that your baby isn't gaining enough.

Curious about how your baby compares with other babies their age? Read more about the average weight and growth for babies, toddlers, and kids.

Learn more:

• Measuring your baby's head circumference, length, and weight
• Baby weight and height percentile calculator
• Child height predictor