Baby Weight Gain Per Month Chart: Complete Guide to Expected Growth Rates

Baby weight gain follows predictable patterns in the first year, with the fastest growth occurring in early months and gradually slowing as babies approach their first birthday. Understanding expected weight gain per month helps you assess whether your baby is growing appropriately and identify patterns requiring evaluation.

Why Weight Gain Per Month Matters

Weight gain velocity (rate of gain over time) often reveals growth patterns that single measurements or percentiles miss:

Pattern detection: A baby at the 50th percentile gaining nothing for 2 months has a problem despite the normal percentile. A baby at the 10th percentile gaining 7 ounces per week is thriving.

Early intervention: Inadequate weight gain identified early allows prompt intervention when it's most effective.

Feeding assessment: Weight gain reflects whether feeding (breast, bottle, or solid foods) provides adequate nutrition.

Growth trajectory: Consistent weight velocity indicates the baby is following their individual growth curve appropriately.

Medical monitoring: Babies with conditions requiring close monitoring benefit from tracking weight velocity between visits.

Expected weight gain changes dramatically throughout the first year as growth velocity naturally slows.

Birth to 2 Weeks: The Initial Weight Loss and Recovery Period

Expected Pattern

Days 1-5:

• Weight loss of 5-10% of birth weight
• Breastfed babies may lose closer to 10%
• Formula-fed babies may lose closer to 5%
• This loss is normal (shedding excess fluid)

Days 5-14:

• Regaining birth weight
• Gain of 0.5-1 ounce per day
• Most babies regain birth weight by day 10-14

By 2 weeks:

• Should be back to birth weight or above
• Failure to regain by 3 weeks needs evaluation

This initial period is unique. Weight loss followed by regain is expected and healthy.

Baby Weight Gain: Month 1 (Weeks 2-6)

Expected Weight Gain

Weekly gain: 5-7 ounces per week

Total month gain: 1.5-2 pounds

From birth weight: Should be 1.5-2 pounds above birth weight by 6 weeks

Month 1 Weight Milestones

This rapid gain reflects frequent feeding (8-12 times per 24 hours) and rapid infant growth velocity.

Baby Weight Gain: Months 2-3

Expected Weight Gain

Weekly gain: 5-7 ounces per week

Monthly gain: 1.5-2 pounds per month

Cumulative: By 3 months, babies typically gain 4.5-6 pounds from birth

Months 2-3 Weight Chart

Growth velocity peaks during months 1-3. This is the fastest weight gain period of human life relative to body size.

Baby Weight Gain: Months 4-6

Expected Weight Gain

Weekly gain: 4-5 ounces per week (months 4-5)

Weekly gain: 3-4 ounces per week (month 6)

Monthly gain: 1-1.5 pounds per month

Cumulative: By 6 months, most babies double their birth weight

Months 4-6 Weight Chart

Notice the gradual deceleration. A baby gaining 6-7 ounces per week at 2 months who slows to 4 ounces per week at 5 months is following the normal pattern, not falling behind.

The 6-Month Double

Doubling birth weight by 5-6 months is a key milestone:

• 7 lb baby reaches 14 lbs
• 8 lb baby reaches 16 lbs
• 9 lb baby reaches 18 lbs

Babies reaching this milestone demonstrate adequate nutrition and healthy growth. Failure to double by 6 months warrants evaluation.

Baby Weight Gain: Months 7-9

Expected Weight Gain

Weekly gain: 2.5-3.5 ounces per week

Monthly gain: 0.7-1 pound per month

Cumulative: Total gain from birth approximately 12-14 pounds by 9 months

Months 7-9 Weight Chart

Growth continues slowing as babies become mobile. Crawling burns significant calories, which can temporarily slow weight gain. This is normal.

Solid Foods Introduction

Most babies begin solid foods around 6 months. During months 7-9:

Breast milk/formula remains primary nutrition: Should provide 70-80% of calories

Solid foods complement: Provide practice eating and additional nutrients but don't replace milk

Weight gain continues from milk: Solids alone don't drive weight gain at this age

Adequate milk intake remains critical for proper weight gain during this period.

Baby Weight Gain: Months 10-12

Expected Weight Gain

Weekly gain: 2-3 ounces per week

Monthly gain: 0.5-0.8 pounds per month

Cumulative: By 12 months, most babies triple their birth weight

Months 10-12 Weight Chart

The 12-Month Triple

Tripling birth weight by 12 months is another key milestone:

• 7 lb baby reaches 21 lbs
• 8 lb baby reaches 24 lbs
• 9 lb baby reaches 27 lbs

Babies achieving this milestone demonstrate consistent adequate growth throughout the first year.

Complete Baby Weight Gain Per Month Chart: Birth to 12 Months

Boys Average Weight Gain by Month

Girls Average Weight Gain by Month

Notice the dramatic deceleration: 2-2.5 pounds per month early on, dropping to 0.6-1 pound per month by the end of the first year.

Factors That Influence Baby Weight Gain

Feeding Method

Breastfed babies:

• May gain slightly slower after month 3-4
• Weight gain patterns used for WHO growth standards
• More variable week-to-week gains

Formula-fed babies:

• Often gain slightly faster, especially after month 3
• More consistent week-to-week gains
• May track higher on WHO charts (which are based on breastfed babies)

Both feeding methods support healthy growth when babies feed on demand and get adequate volume.

Birth Weight and Prematurity

Low birth weight babies: May gain faster initially (catch-up growth) or slower if complications exist

High birth weight babies: May gain slightly slower as they find their genetic growth curve

Premature babies: Use corrected age (adjusted for prematurity) when comparing to charts. Many show catch-up growth in first 2-3 years.

Genetics

Tall, large parents typically have babies who gain faster and track higher percentiles. Short, small parents typically have babies who gain slower and track lower percentiles. By 6-12 months, babies often settle into the growth curve reflecting their genetic potential.

Illness and Teething

Temporary slowdowns or brief weight loss during illness are common. Weight gain typically resumes once baby recovers. Frequent illnesses can affect overall growth trajectory.

Teething may temporarily reduce appetite but shouldn't significantly impact weight gain over multiple months.

Activity Level

Mobile babies (crawling, cruising, walking) burn more calories. Weight gain naturally slows when babies become active. This is healthy and expected.

When Weight Gain Per Month Indicates Concerns

Inadequate Weight Gain

Contact your pediatrician if:

Newborns (0-6 months):

• Not regaining birth weight by 3 weeks
• Gaining less than 4 ounces per week for 2+ weeks
• No weight gain for 2 weeks
• Weight loss after regaining birth weight

Older babies (6-12 months):

• Gaining less than 2 ounces per week for 1 month
• No weight gain for 1 month
• Weight loss over multiple weeks

Any age:

• Crossing 2+ percentile curves downward
• Dropping from previously established growth curve
• Poor feeding, decreased output (wet diapers), or lethargy

Possible causes include inadequate milk intake, feeding difficulties, reflux, food allergies, metabolic disorders, or chronic conditions.

Excessive Weight Gain

Contact your pediatrician if:

Any age:

• Gaining significantly more than expected rates for 2+ months
• Crossing 2+ percentile curves upward rapidly
• Weight percentile 2+ bands higher than length percentile
• Family history doesn't explain rapid gain

Possible causes include overfeeding, improper formula preparation, or rarely, medical conditions.

Most excessive gain in formula-fed babies reflects overfeeding and responds to adjusted feeding volumes.

Breastfed vs. Formula-Fed Weight Gain Patterns

Breastfed Babies

Months 0-3: Similar to formula-fed babies (5-7 oz per week)

Months 4-12: Often slightly slower gain than formula-fed babies

Variability: More week-to-week variation (difficult to measure exact intake)

WHO charts: Based on breastfed babies, so breastfed babies typically track curves well

Concern threshold: Same as formula-fed babies for minimum adequate gain

Formula-Fed Babies

Months 0-3: Similar to breastfed babies (5-7 oz per week)

Months 4-12: Often slightly faster gain than breastfed babies

Consistency: More consistent week-to-week (intake is measurable)

WHO charts: May track slightly higher than curves (curves based on breastfed babies)

Monitoring: Watch for excessive gain above expected rates

Both methods support healthy growth. The feeding method matters less than whether baby gains adequately and maintains their growth curve.

Calculating Your Baby's Weight Gain

Weekly Weight Gain

Formula: (Current weight - previous weight) / weeks between measurements = weekly gain

Example: Baby weighed 12 lbs at 2 months, 14 lbs at 3 months

• Weight gain: 14 - 12 = 2 lbs = 32 oz
• Time period: 4 weeks
• Weekly gain: 32 oz / 4 weeks = 8 oz per week

Compare to age-expected rates to assess adequacy.

Monthly Weight Gain

Formula: (Current weight - previous weight) / months between measurements = monthly gain

Example: Baby weighed 17.5 lbs at 6 months, 20.1 lbs at 9 months

• Weight gain: 20.1 - 17.5 = 2.6 lbs
• Time period: 3 months
• Monthly gain: 2.6 lbs / 3 months = 0.87 lbs per month

Compare to age-expected monthly gains.

Home Weighing for Tracking Weight Gain

Equipment: Digital baby scale (accuracy to 0.5-1 oz)

Frequency:

• Weekly (months 0-3 if monitoring concerns)
• Every 2 weeks (months 0-6 for routine tracking)
• Monthly (months 6-12)

Technique:

• Same time of day (before first morning feed)
• Diaper only or naked
• Same scale
• Average 2-3 readings if inconsistent

Recording:

• Date and age
• Weight
• Time of day
• Notes (fed recently, clothing worn)

Home weighing supplements, not replaces, pediatrician measurements. Bring home data to appointments.

The Bottom Line on Baby Weight Gain Per Month

Baby weight gain per month follows a predictable pattern: rapid gain of 5-7 oz per week during months 0-3, gradually slowing to 2-3 oz per week by months 10-12. This dramatic deceleration is normal and expected as infant growth velocity naturally slows.

Key milestones include doubling birth weight by 5-6 months and tripling birth weight by 12 months. Babies achieving these milestones and maintaining consistent growth curves are thriving.

What matters most is consistent weight velocity appropriate for age. Track weight gain systematically, compare to age-expected rates, and contact your pediatrician when gain is inadequate (below minimums for 2+ weeks), excessive (significantly above expectations), or when baby crosses 2+ percentile curves in either direction.

Remember that healthy babies exist across all percentiles. The specific percentile matters less than consistent gain along that curve. Week-to-week fluctuations are normal; focus on trends over multiple weeks.

References

1. World Health Organization. WHO Child Growth Standards. Available at: https://www.who.int/tools/child-growth-standards
2. Centers for Disease Control and Prevention. Infant Weight Gain Guidelines. Available at: https://www.cdc.gov/growthcharts/
3. American Academy of Pediatrics. Bright Futures Guidelines - Infant Nutrition. Available at: https://brightfutures.aap.org/
4. Dewey KG, et al. Growth of Breast-fed and Formula-fed Infants. WHO Working Group. 1998.
5. Koletzko B, et al. Growth of Infants. Pediatric Gastroenterology and Nutrition. 2006.