Most babies gain about 1.5 to 2 pounds per month during the first three months of life, then gradually slow to about 1 to 1.25 pounds per month between four and six months. By the second half of the first year, weight gain slows even further. These are averages, and healthy babies can fall above or below them, but knowing the general pattern helps you spot whether your baby’s growth is on track.
The First Two Weeks: Losing Before Gaining
Before babies start putting on weight, they lose some. Newborns typically drop 7 to 10 percent of their birth weight in the first few days as their bodies shed extra fluid. A baby born at 8 pounds might dip to about 7 pounds 4 ounces before the trend reverses. Full-term babies usually regain their birth weight within 7 to 10 days. Premature babies take longer, often 10 to 15 days or more.
This initial dip is normal and expected. Pediatricians watch for it at the first few checkups and will flag any baby who hasn’t returned to birth weight by two weeks.
Birth to Three Months: The Fastest Growth
Once babies recover their birth weight, growth takes off. Newborns gain roughly 1 ounce per day (about 30 grams) during the first three months. That works out to approximately 1.5 to 2 pounds each month, though some healthy babies gain a bit more or less.
Growth isn’t perfectly steady during this stretch. Babies commonly hit growth spurts around 2 to 3 weeks and again at about 6 weeks. During a spurt, your baby may want to eat more frequently, sometimes clustering feedings close together for a day or two. This is temporary and usually resolves within a few days.
Four to Six Months: Growth Begins to Slow
Around four months, daily weight gain drops to about 20 grams (roughly two-thirds of an ounce). Children’s Hospital of Philadelphia puts the average at 1 to 1.25 pounds per month during this window. Another growth spurt commonly happens around three months, and a second around six months.
Many babies start solid foods somewhere in this range, but introducing solids doesn’t typically cause a noticeable jump in weight gain. Breast milk or formula still provides the majority of calories.
Seven to Twelve Months: A Gentler Pace
By six months, many babies are gaining about 10 grams or less per day, which translates to roughly half a pound to one pound per month. This slowdown is completely normal. Babies are burning more energy now because they’re rolling, sitting up, crawling, and eventually pulling to stand.
A useful rule of thumb: most babies double their birth weight by about five months and triple it by their first birthday. A baby born at 7.5 pounds would be expected to weigh somewhere around 22 to 23 pounds at age one, though there’s a wide healthy range.
Breastfed vs. Formula-Fed Babies
Breastfed and formula-fed babies grow at similar rates in the first few months, but their patterns diverge after about three months. Formula-fed infants typically gain weight more quickly in the second half of the first year, while breastfed babies put on weight more slowly. This difference persists even after babies start eating solid foods.
The CDC and American Academy of Pediatrics recommend using the World Health Organization (WHO) growth charts for all children from birth to age two, regardless of how they’re fed. The WHO charts are based on breastfed infants and reflect how babies should grow under optimal conditions, rather than simply how they do grow in a particular population. If your pediatrician is using the older CDC charts, a healthy breastfed baby might appear to “fall off” their curve after a few months when they’re actually growing normally.
What Growth Charts Actually Tell You
Pediatricians don’t just look at a single weight. They track your baby’s growth over time on a percentile curve. A baby in the 25th percentile isn’t underweight. It means 25 percent of babies weigh less and 75 percent weigh more. What matters most is consistency: a baby who has been tracking along the 25th percentile and continues to do so is growing well.
The concern arises when a baby crosses two or more major percentile lines on the chart, either up or down. Dropping from the 50th percentile to below the 10th over a couple of visits, for example, would prompt a closer look. A weight-for-age below the 5th percentile is one of the accepted markers for failure to thrive, though pediatricians also consider length, head circumference, feeding patterns, and the baby’s overall behavior before reaching that diagnosis.
Signs Your Baby Is Getting Enough
Between weigh-ins at the pediatrician’s office, a few everyday signals tell you whether feeding is going well. In the first month, look for six or more wet diapers a day and three to four stools. Your baby should seem satisfied after feedings, have good skin tone, and be alert during wake periods. After the first month, stool frequency can vary widely, especially in breastfed babies, so wet diapers and overall demeanor are more reliable indicators than counting dirty diapers.
If you’re weighing your baby at home, accuracy matters. Use the same scale each time, weigh the baby in just a diaper, and make sure the baby is centered on the scale and not touching anything else. Common sources of error include not zeroing the scale before each use, leaving clothes on, or weighing at different times of day. A baby can easily weigh a few ounces more after a feeding than before one, so try to be consistent about timing.
When Weight Gain Is Too Slow or Too Fast
Babies who consistently gain less than expected may not be taking in enough calories. Common reasons include difficulty latching, low milk supply, tongue tie, reflux, or an underlying medical condition. Slow gain doesn’t always mean something is wrong, but a pattern of falling behind deserves evaluation.
Rapid weight gain in infancy has its own considerations. Consistently crossing percentile lines upward, especially with formula-fed babies, may signal overfeeding. Some research links very rapid infant weight gain with higher risk of childhood obesity, though genetics and many other factors play a role.
The most practical thing you can do is keep your baby’s well-child appointments. Those regular weigh-ins, plotted on the WHO growth chart, give a far more reliable picture than any single number on a scale.