Quick Answer:

A normal weight gain for babies is approximately 5 to 7 ounces per week during the first 4 to 6 months of life, and about 3 to 5 ounces per week from 6 to 12 months. Most healthy babies double their birth weight by 4 to 5 months and triple it by their first birthday. Newborns typically lose 5 to 10 percent of their birth weight in the first few days after birth, which is completely normal, and then regain it within 10 to 14 days.

Why Baby Weight Gain Matters

Few things fill a new parent’s mind quite like the question: “Is my baby growing the way they should?” It is one of the most common concerns we hear at Idaho Falls Pediatrics, and it is a completely understandable one. Weight is one of the clearest, most measurable signs that your baby is well-fed, healthy, and thriving.

That said, healthy babies come in all shapes and sizes. What matters is not a single number on the scale, but a consistent pattern of growth over time. This guide walks you through what to expect month by month during your baby’s first year, what influences those numbers, and when it is a good idea to reach out to your pediatrician.

Understanding Baby Weight: The Basics Before Month 1

Before we dive into the monthly milestones, there are a few foundational things every parent should know.

Average Birth Weight

The average full-term newborn weighs between 5 pounds 8 ounces and 8 pounds 13 ounces (approximately 2.5 to 4 kg). Babies born outside of this range are not automatically unhealthy, but your care team will monitor their growth closely.

The Initial Weight Drop (And Why It Happens)

Almost every newborn loses weight in the first three to five days of life. This is expected and normal. Babies are born with extra fluid in their bodies, and they pass it through urine and stool during those first days. Most newborns lose between 5 and 10 percent of their birth weight during this window.

A loss of more than 10 percent of birth weight in the newborn period is something your pediatrician will want to monitor closely, as it can sometimes signal feeding challenges.

Regaining Birth Weight

Healthy babies typically regain their birth weight by 10 to 14 days of age. If your baby is not back to their birth weight by two weeks, your pediatrician at Idaho Falls Pediatrics will want to see them to assess feeding and overall health.

Growth Charts: The Tool Your Pediatrician Uses

Pediatricians track infant weight using standardized growth charts developed by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). These charts plot your baby’s weight, length, and head circumference against other babies of the same age and sex. The goal is not for your child to hit a certain percentile, but to grow consistently along their own curve over time.

A baby consistently in the 15th percentile is just as healthy as one in the 85th, provided their growth pattern is steady and their development is on track.

Baby Weight Gain: 12 Monthly Milestones

The following milestones are based on general pediatric guidelines. Every baby is unique, and these ranges represent typical patterns rather than rigid rules. Use these as a helpful reference, not a report card.

Newborn (Birth to 2 Weeks)

• Expected weight: Average of 5 lbs 8 oz to 8 lbs 13 oz at birth
• Normal pattern: Lose 5 to 10 percent of birth weight in the first 3 to 5 days, then begin regaining
• Goal by end of this period: Return to birth weight by day 10 to 14

This is when feeding gets established. Whether you are breastfeeding or formula feeding, frequent feeds (8 to 12 times per day for breastfed newborns) support healthy early weight gain. Wet diapers are one of the best indicators that your baby is getting enough to eat.

Month 1 (2 Weeks to 1 Month)

• Expected weekly gain: 5 to 7 ounces per week
• Total gain this month: Approximately 1.5 to 2 pounds above birth weight

By the end of the first month, most babies are noticeably heavier than when they came home from the hospital. You will likely notice your newborn starting to fill out, with rounder cheeks and thighs. Your baby’s first well-child visit typically occurs at 3 to 5 days and again at 1 month. These visits are a perfect time to ask your provider at Idaho Falls Pediatrics any feeding or growth questions.

Month 2

• Expected weekly gain: 5 to 7 ounces per week
• Total gain by end of month 2: Typically 2 to 4 pounds above birth weight

Month 2 brings more wakefulness and social smiles. Your baby’s appetite is growing, and so is their body. Breastfed babies may feed more frequently during growth spurts, which can sometimes worry parents into thinking their milk supply is low. Usually, this increased feeding is simply your baby’s way of boosting supply to meet demand.

Month 3

• Expected weekly gain: 5 to 7 ounces per week
• What to watch: Growth spurts are common around 3 months

By month 3, many babies have gained roughly 2 to 4 pounds since birth and grown an inch or two in length. Your baby is becoming more active, more aware of their surroundings, and may be holding their head up steadily during tummy time. The 2-month well-child visit (typically scheduled slightly before or at this point) includes vaccinations and a full growth assessment. You can learn more about our vaccine schedule here.

Month 4

• Expected weekly gain: 5 to 7 ounces per week
• Milestone: Many babies are approaching double their birth weight by this point

The 4-month mark is often when parents first start hearing questions about solid foods. The American Academy of Pediatrics (AAP) recommends waiting until around 6 months of age before introducing solids, though some babies may show readiness signs slightly earlier. Always talk to your pediatrician before starting solids. Your baby’s continued weight gain at this stage is primarily driven by breast milk or infant formula.

Month 5

• Expected weekly gain: 5 to 7 ounces per week
• Milestone: Most babies have doubled their birth weight by 4 to 5 months

By 5 months, your baby is becoming increasingly interactive, rolling over, and possibly starting to reach and grasp for objects. These motor developments actually burn more calories, but continued frequent feeding keeps growth on track. If your baby has doubled their birth weight and is growing along their growth curve, things are going well.

Month 6

• Expected weekly gain: Rate begins to slow to approximately 3 to 5 ounces per week
• Milestone: The 6-month well-child visit is one of the most important of the first year

Month 6 is a major transition. Growth naturally slows a bit as your baby becomes more mobile. This is also when many families begin introducing pureed solid foods alongside breast milk or formula. It is important to understand that at this stage, solids are meant to complement milk feeds, not replace them. Breast milk or infant formula remains the primary nutrition source through the first year.

Your 6-month well-child visit at Idaho Falls Pediatrics will include a full review of your baby’s growth chart, a developmental screening, and vaccinations.

Month 7

• Expected weekly gain: 3 to 5 ounces per week
• What to expect: Sitting up, more activity, expanding palate for solid foods

By 7 months, most babies are sitting with some support or independently. Increased physical activity means calorie demands remain high. Expanding solid food variety at this stage, alongside continued breast milk or formula, supports healthy weight gain and iron intake.

Month 8

• Expected weekly gain: 3 to 5 ounces per week
• What to expect: Crawling begins, energy demands increase

Mobility is ramping up. Many babies start crawling around month 8, which significantly increases their daily energy output. Some parents notice a brief plateau or slight slowdown in weight gain as their baby gets more active. This is generally normal, but if your baby’s weight drops off their growth curve, schedule an appointment with your pediatrician.

Month 9

• Expected weekly gain: 3 to 5 ounces per week
• Well-child visit: The 9-month checkup is a key milestone for developmental screening

The 9-month visit is important not just for weight but for developmental milestones like babbling, object permanence, and emerging fine motor skills. Weight gain is typically steady, and your baby may now be eating a wider variety of soft finger foods. Your pediatrician will review whether your baby is following their growth curve and meeting developmental benchmarks.

Month 10

• Expected weekly gain: 3 to 5 ounces per week
• What to expect: Pulling to stand, cruising along furniture

As your baby begins pulling up to stand and cruising along furniture, their activity level climbs further. Good nutrition, including continued breast milk or formula and a variety of age-appropriate solid foods, continues to support healthy growth. Iron-rich foods become especially important around this age.

Month 11

• Expected weekly gain: 3 to 5 ounces per week
• What to expect: Preparing for the transition toward whole milk after 12 months

Month 11 brings your baby close to a major nutritional transition. Breast milk or infant formula should still be the primary drink until 12 months of age. Some babies will begin to show preferences for certain solid foods, and that is completely normal. Keep offering variety and let your baby self-regulate their intake.

Month 12 (1 Year)

• Expected total weight: Approximately triple birth weight
• Milestone: The 12-month well-child visit marks the end of infancy and the beginning of toddlerhood

By their first birthday, most babies have tripled their birth weight. A baby who weighed 7.5 pounds at birth will typically weigh around 22 to 23 pounds at 12 months, though healthy variation above or below this is common. The 12-month well-child visit is one of the most comprehensive of the entire first year. It includes a full growth assessment, developmental screening, anemia screening, and vaccinations, including the measles-mumps-rubella (MMR) vaccine.

After 12 months, your baby transitions to whole cow’s milk (if not breastfeeding), and the focus of nutrition begins to shift more toward a varied, balanced diet.

What Affects Baby Weight Gain?

Several factors influence how a baby grows, and understanding them helps parents see the bigger picture.

• Feeding method: Breastfed and formula-fed babies can grow at slightly different rates, particularly in the early months. Both are healthy when feeding is going well.
• Genetics: Parental height and build play a significant role in where a baby falls on the growth chart.
• Birth weight: Premature babies and small-for-gestational-age infants follow adjusted growth expectations and are monitored on specialized charts.
• Health conditions: Certain underlying medical conditions, such as reflux, food intolerances, congenital heart defects, or metabolic disorders, can affect weight gain and require evaluation.
• Activity level: As babies become more mobile, the rate of weight gain naturally slows.
• Growth spurts: Babies do not grow at a perfectly steady rate. Brief periods of rapid gain are interspersed with slower stretches.

When Should You Call Your Pediatrician About Baby Weight?

While gentle growth patterns vary widely, there are certain signs that warrant a call to your child’s doctor. Reach out to your provider at Idaho Falls Pediatrics if you notice any of the following:

• Your newborn has lost more than 10 percent of their birth weight
• Your baby has not regained birth weight by 2 weeks of age
• Your baby is consistently falling off their established growth curve
• Your baby seems consistently unsatisfied after feedings
• You are seeing fewer than the expected number of wet diapers per day
• Your baby is not gaining weight over a 2-week period after the newborn phase
• Your baby seems lethargic, is feeding very poorly, or appears unwell

These concerns do not always mean something is seriously wrong, but they are worth evaluating promptly. Our team is here to help you figure out what is going on and get your baby back on track.

Not sure if what you are seeing is normal? Use our Symptom Checker as a first step, and never hesitate to call us.

Breastfed vs. Formula-Fed Babies: Is There a Difference in Weight Gain?

This is a question we hear often at Idaho Falls Pediatrics, and the answer is nuanced.

In the first few months, formula-fed babies sometimes gain weight slightly faster than breastfed babies. Breastfed babies tend to self-regulate their intake very well, which can result in leaner, but entirely healthy, growth patterns. After 6 months, growth rates between breastfed and formula-fed babies typically even out.

The WHO growth charts used by most American pediatricians today were actually developed using data from breastfed infants as the reference standard. This is important to know because older CDC growth charts were based on predominantly formula-fed populations. If your doctor uses the WHO charts (as most do for children 0 to 2 years), the reference standard already reflects breastfed growth patterns.

The bottom line: both feeding methods can absolutely support healthy weight gain. What matters most is that your baby is feeding consistently, producing adequate wet diapers, and following their growth curve over time.

The Role of Well-Child Visits in Monitoring Baby Weight

Consistent well-child visits are the single best tool for monitoring your baby’s growth and catching any concerns early. The American Academy of Pediatrics recommends well-child checkups at the following ages during the first year:

• 3 to 5 days old
• 1 month
• 2 months
• 4 months
• 6 months
• 9 months
• 12 months

At each of these visits, your baby’s weight, length, and head circumference are plotted on a growth chart. Your pediatrician reviews the pattern over time, not just the individual numbers. These visits also include developmental screenings, vaccinations, and a chance for you to ask every question on your list.

At Idaho Falls Pediatrics, our providers take the time to go through your baby’s growth trends with you, explain what they mean, and make sure you leave feeling informed and confident. Learn why choosing a board-certified pediatrician matters for your child’s health.

FAQ: Normal Weight Gain for Babies

Q: How much weight should a newborn gain per week?

A: In the first 4 to 6 months of life, most newborns gain approximately 5 to 7 ounces per week. After 6 months, the rate slows to around 3 to 5 ounces per week as babies become more active.

Q: Is it normal for a newborn to lose weight after birth?

A: Yes. Losing 5 to 10 percent of birth weight in the first few days is completely normal. Most babies regain that weight within 10 to 14 days.

Q: When should a baby double their birth weight?

A: Most healthy babies double their birth weight between 4 and 5 months of age.

Q: When should a baby triple their birth weight?

A: Most babies triple their birth weight by their first birthday at 12 months.

Q: My baby seems to have stopped gaining weight. Should I worry?

A: Brief plateaus can happen, especially around growth spurts or when a baby becomes more active. However, if your baby is not gaining weight over a two-week period beyond the newborn stage, or if their weight is dropping off their growth curve, it is worth calling your pediatrician.

Q: Do breastfed babies gain weight differently than formula-fed babies?

A: They can, particularly in the first few months. Breastfed babies often have a slightly leaner growth pattern but still follow a healthy curve. Both feeding methods support healthy weight gain when going well. Your pediatrician tracks both using the same WHO growth charts.

Q: What percentile should my baby be for weight?

A: There is no single “right” percentile. A baby in the 10th percentile is just as healthy as a baby in the 90th, as long as they are growing consistently along their own curve. What matters is sustained, steady growth over time, not a specific number.

Q: What are signs my baby is not getting enough to eat?

A: Signs may include fewer than expected wet diapers (less than 6 per day after day 5), consistent fussiness after feeds, failure to regain birth weight, or weight that is dropping off the growth curve. Contact your pediatrician if you are concerned.

Q: When can babies start solid foods?

A: The American Academy of Pediatrics recommends introducing solid foods around 6 months of age, alongside continued breast milk or formula. Always consult your pediatrician before starting solids.

Q: How do I know if my baby’s growth is on track between visits?

A: Look for consistent hunger and feeding cues, regular wet and dirty diapers, alert and content periods between feeds, and steady weight gain at well-child visits. If you are unsure, your pediatric team is always just a phone call away.

We Are Here to Help Your Baby Grow and Thrive

Every baby’s growth story is a little different, and that is exactly why having a trusted pediatrician in your corner matters so much. Whether you have questions about your newborn’s feeding, your 6-month-old’s growth curve, or what to expect at the one-year visit, the team at Idaho Falls Pediatrics is here for you.

We serve families across Idaho Falls, Ammon, and Rexburg from three convenient locations. Schedule an appointment today or explore our patient resources to learn more about keeping your child healthy at every stage.

The content on this page is intended for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your child’s board-certified pediatrician regarding your baby’s individual growth and health needs.