Most newborns gain about 1.5 to 2 pounds per month for the first three months of life, making it the fastest growth period of their entire first year. After that, the rate gradually slows: babies typically gain about 1 to 1.25 pounds per month from 4 to 6 months, then roughly 1 pound per month from 7 to 12 months. These are averages, and healthy babies can fall above or below them while still growing normally.
The First Week: Expect Weight Loss, Not Gain
Before the gaining starts, nearly all newborns lose weight. Babies shed excess fluid in the first few days, and most begin regaining weight between days 3 and 5. About 80 percent of babies are back to their birth weight by two weeks of age. A loss of up to 7 or 8 percent of birth weight is considered normal. If a newborn loses more than 10 percent, that signals a need for closer evaluation of feeding.
During this window, tracking wet and soiled diapers is one of the simplest ways to tell if your baby is eating enough. After day 5, a well-fed newborn produces at least 6 wet diapers per day.
Birth to 3 Months: The Fastest Growth
Once babies regain their birth weight, they enter the most rapid growth phase. Weight gain during this stretch averages about 5 to 7 ounces per week, which works out to roughly 1.5 to 2 pounds per month. Some weeks your baby may gain more, others less, and that’s completely normal as long as the overall trend is upward.
Growth spurts can make certain weeks feel more intense than others. Babies commonly hit spurts around 2 to 3 weeks, 6 weeks, and 3 months. During a spurt, your baby may want to feed more frequently for a few days before settling back into a more predictable pattern. These spurts usually last only a few days, but they can be exhausting for parents.
4 to 6 Months: Growth Starts to Slow
Weight gain naturally decelerates around the 4-month mark. Babies in this age range typically gain 1 to 1.25 pounds per month, according to Children’s Hospital of Philadelphia. The daily gain drops from roughly an ounce a day in the early months to about two-thirds of an ounce. Another growth spurt often hits around 6 months, temporarily increasing appetite again.
A major milestone falls in this window: most babies double their birth weight by 4 to 5 months. So a baby born at 7.5 pounds would typically weigh around 15 pounds by that point. If your baby was premature or had a low birth weight, the timeline may look different, and your pediatrician will track growth using adjusted age.
7 to 12 Months: A Steadier, Slower Pace
From 7 months through the first birthday, average weight gain settles to about 1 pound per month. Daily gain drops to around a third of an ounce or less. This slowdown is normal and reflects the fact that babies are now spending more energy on movement, sitting up, crawling, and eventually pulling to stand.
By 12 months, most babies have tripled their birth weight. A baby born at 7.5 pounds would weigh roughly 22 to 23 pounds at their first birthday. This is a useful ballpark, not a strict target. Babies who were born larger or smaller will naturally land at different numbers while following the same healthy growth curve.
Breastfed vs. Formula-Fed Growth Patterns
Breastfed and formula-fed babies grow at different rates, and neither pattern is “wrong.” Healthy breastfed infants typically put on weight more slowly than formula-fed infants over the first year. The difference becomes more noticeable after about 3 months, when formula-fed babies tend to gain weight more quickly. This gap persists even after solid foods are introduced.
This matters because the growth chart your pediatrician uses can affect how your baby’s weight is interpreted. The WHO growth charts are based on breastfed infants and treat breastfeeding as the biological norm. The CDC growth charts were built from data on predominantly formula-fed babies. If a breastfed baby is plotted on a CDC chart, they may appear to be gaining too slowly when they’re actually growing exactly as expected. Most pediatricians in the U.S. use the WHO charts for children under 2 for this reason.
When Weight Gain Is Too Slow
Pediatricians look at growth trends over time rather than any single weigh-in. A baby who has always tracked along the 15th percentile is growing consistently, even though they’re smaller than most peers. What raises concern is a pattern of falling away from the baby’s own established curve.
Clinically, poor weight gain is flagged when a baby’s weight drops below the 5th percentile for age and sex, or when their growth crosses downward by two major percentile lines on the growth chart. For example, a baby who was at the 50th percentile and drops to the 10th over a few months would warrant closer attention. Causes range from feeding difficulties and food sensitivities to medical conditions that affect nutrient absorption.
Some practical signs at home that a baby may not be getting enough nutrition include fewer than 6 wet diapers a day after the first week, persistent fussiness after feeds, and visible lethargy. These don’t automatically mean something is wrong, but they’re worth mentioning at your next visit.
Month-by-Month Summary
- Birth to 1 month: 1.5 to 2 lbs (after regaining birth weight)
- 1 to 3 months: 1.5 to 2 lbs per month
- 4 to 6 months: 1 to 1.25 lbs per month
- 7 to 12 months: about 1 lb per month
By 4 to 5 months, expect roughly double the birth weight. By 12 months, roughly triple. These milestones give you a quick way to gauge whether your baby’s overall trajectory is on track, even without memorizing exact ounce-per-week numbers.