Baby Weight Gain: What's Normal in the First Year

"Is my baby gaining enough weight?" It's one of the most common questions parents ask. Weight gain is a key indicator that babies are eating well and growing healthily.

Here's what you should know about baby weight gain patterns.

Important: Growth patterns vary significantly between babies. Your pediatrician tracks your individual baby's growth over time. The general information below doesn't replace personalized medical guidance.

The First Week

It's normal for newborns to lose weight in the first few days after birth. The AAP notes that babies typically lose 5 to 7 percent of their birth weight, sometimes up to 10 percent.

This happens because babies are born with extra fluid that they lose after birth, and they're still learning to feed efficiently.

By day 4 or 5, weight should stabilize and start increasing. Most babies regain their birth weight by 10 to 14 days old.

If your baby loses more than 10 percent or doesn't start gaining by day 5, your pediatrician will want to assess feeding and may recommend additional support.

General Weight Gain Patterns

After regaining birth weight, typical weight gain looks something like this:

0 to 3 months: About 5 to 7 ounces per week.

4 to 6 months: About 4 to 5 ounces per week. Growth rate naturally slows.

6 to 12 months: About 3 to 4 ounces per week. Even slower, which is normal.

Doubling birth weight: Usually around 4 to 5 months.

Tripling birth weight: Usually around 12 months.

These are averages. Your baby might gain more or less in any given week, and that's usually fine. What matters is the pattern over time.

How Pediatricians Track Growth

At well-child visits, your pediatrician measures weight, length, and head circumference. These are plotted on growth charts that show percentiles.

Percentiles compare your baby to other babies of the same age. A baby in the 25th percentile weighs more than 25% of babies their age and less than 75%. Neither high nor low percentiles are inherently good or bad.

What pediatricians look for:

Consistent growth along a curve: A baby who's been in the 30th percentile and stays around there is growing well, even though they're smaller than average.

Crossing percentile lines: If a baby drops from the 50th to the 10th percentile over several months, that warrants investigation. Same if they jump dramatically upward.

Proportionate growth: Weight, length, and head circumference should generally track together.

Breastfed vs. Formula Fed

Breastfed and formula-fed babies may have slightly different growth patterns.

Breastfed babies often grow faster in the first few months, then slower in the second half of the first year. Formula-fed babies may show more steady growth throughout.

The WHO growth charts are based on breastfed babies and are now recommended for all infants in the first 2 years. Your pediatrician uses appropriate charts for comparison.

When Parents Worry

It's easy to worry about weight. Common concerns include:

Baby seems small: Some babies are naturally petite, just like some adults are. If growth is consistent on their own curve, they're likely fine.

Baby isn't eating as much as before: Intake naturally decreases relative to body weight as babies grow. They're also more efficient eaters.

Other babies seem bigger: Comparing to other babies isn't useful. Each baby has their own growth pattern.

Weight gain slowed: Growth rate naturally slows after the first few months. This is expected.

The best approach is to discuss any concerns with your pediatrician. They can assess whether growth is tracking appropriately.

Signs to Watch For

Talk to your pediatrician if:

Your newborn isn't back to birth weight by 2 weeks. Baby seems consistently unsatisfied after feeds. Diaper output is low (fewer wet or dirty diapers than expected). Baby seems lethargic or weak. You notice significant changes in eating patterns.

Your pediatrician is your partner in monitoring growth. Don't hesitate to reach out between visits if you're concerned.

Tracking at Home

While you don't need to weigh your baby at home, tracking feeding can give you confidence that intake is adequate.

Logging feeds helps you see patterns: how often baby eats, how long nursing sessions last, or how much formula is consumed. This information is useful context if you ever have concerns about weight gain.

Growth tracking features let you log weight measurements from pediatrician visits and see the trajectory over time.

The Big Picture

Weight gain is one indicator of health, but it's not the only one. A baby who's gaining appropriately, meeting developmental milestones, seems alert and engaged, has adequate diaper output, and is generally content is likely thriving, regardless of percentile.

Trust your pediatrician's assessment. They see hundreds of babies and can distinguish between normal variation and genuine concerns.

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BabyZone helps you track growth measurements from pediatrician visits and log daily feeding to monitor intake patterns.

This article is for informational purposes only and does not constitute medical advice. Discuss any growth concerns with your pediatrician.