Feeding & Eating

I'm Worried My Baby Isn't Growing (Failure to Thrive)

Medically reviewed by Dr. Rachel Kim, MD, RDN · Pediatric Nutrition Specialist

Content reviewed against published AAP, WHO, CDC guidelines

Editorial policy

Last reviewed:

Feeding challenges are one of the most common concerns new parents face. When it comes to i'm worried my baby isn't growing (failure to thrive), here is what the guidelines recommend.

The short answer

Failure to thrive, now often called growth faltering, means a baby is not gaining weight or growing as expected. It is important to know that babies naturally shift percentiles in their first two years, and being on a lower percentile is not the same as failure to thrive. True growth faltering involves crossing two or more major percentile lines downward and usually requires medical evaluation to determine the cause.

Key takeaways

  • Failure to thrive, now often called growth faltering, means a baby is not gaining weight or growing as expected. It is important to know that babies naturally shift percentiles in their first two years, and being on a lower percentile is not the same as failure to thrive. True growth faltering involves crossing two or more major percentile lines downward and usually requires medical evaluation to determine the cause.
  • Usually normal when: Your baby is on a lower percentile but has been growing steadily along their own curve since birth
  • Call your doctor if: Your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds
  • Varies by age — see the age-by-age breakdown below
“The AAP recommends exclusive breastfeeding for approximately 6 months after birth. Furthermore, the AAP supports continued breastfeeding, along with appropriate complementary foods introduced at about 6 months, for 2 years or beyond.”
— Breastfeeding and the Use of Human Milk, American Academy of Pediatrics (AAP)

Thousands of parents search for this exact thing. You are not alone.

What Parents Should Know

According to AAP, WHO, CDC guidelines, failure to thrive, now often called growth faltering, means a baby is not gaining weight or growing as expected. It is important to know that babies naturally shift percentiles in their first two years, and being on a lower percentile is not the same as failure to thrive. True growth faltering involves crossing two or more major percentile lines downward and usually requires medical evaluation to determine the cause. At 0-3 months, weight gain in the first three months is typically rapid, averaging about 5 to 7 ounces per week. After an initial weight loss of up to 7 to 10 percent of birth weight in the first few days, babies should regain their birth weight by 10 to 14 days. If your baby has not regained birth weight by two weeks or is gaining less than 4 ounces per week, your pediatrician will want to evaluate feeding. Common causes at this age include difficulty latching, low milk supply, tongue tie, or formula preparation errors. It is generally considered normal when your baby is on a lower percentile but has been growing steadily along their own curve since birth. However, you should contact your pediatrician promptly if your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds.

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal
Worth Discussing
Your baby is on a lower percentile but has been growing steadily along their own curve since birth
Your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds
Your baby dropped from a higher percentile to a lower one in the first 6 months and then stabilized, which often reflects finding their genetic growth pattern
Your baby has signs of dehydration such as no tears when crying, sunken fontanelle, very few wet diapers, or dry cracked lips
Your baby's weight dipped slightly during an illness but bounced back within a week or two
Your baby has crossed two or more major percentile lines downward on the growth chart
Both parents are small in stature, and your baby is tracking along a lower percentile consistently
Your baby seems hungry all the time but is not gaining weight despite frequent feeds

By Age

What to expect by age

0-3 months

Weight gain in the first three months is typically rapid, averaging about 5 to 7 ounces per week. After an initial weight loss of up to 7 to 10 percent of birth weight in the first few days, babies should regain their birth weight by 10 to 14 days. If your baby has not regained birth weight by two weeks or is gaining less than 4 ounces per week, your pediatrician will want to evaluate feeding. Common causes at this age include difficulty latching, low milk supply, tongue tie, or formula preparation errors.

3-6 months

Growth velocity naturally slows slightly at this age but should remain steady. Babies typically gain about 3 to 5 ounces per week. If your baby's weight has crossed two or more major percentile lines on the growth chart, your pediatrician may want to investigate. It is worth noting that breastfed and formula-fed babies have different growth patterns, and the WHO growth charts, which are based primarily on breastfed babies, are recommended for all infants under 2 years.

6-12 months

As babies become more active with crawling and exploring, weight gain naturally slows to about 2 to 3 ounces per week. The introduction of solids sometimes leads to a temporary plateau as babies adjust. If your baby is losing weight or consistently dropping percentiles despite adequate feeding opportunities, your pediatrician may check for underlying causes such as food allergies, celiac disease, or metabolic conditions. Most cases of growth faltering at this age are related to caloric intake rather than a medical condition.

12-24 months

Toddlers grow more slowly than infants, and their weight gain may only be 3 to 5 pounds over the entire second year of life. Picky eating is very common at this age and can make parents anxious about growth, but most picky toddlers grow fine. If your toddler has dropped significantly on their growth curve, your pediatrician will likely evaluate their diet, look for underlying conditions, and may refer you to a pediatric nutritionist. The goal is to identify whether the issue is insufficient intake, increased caloric needs, or poor absorption.

What to Tell Your Pediatrician

  • Describe when you first noticed i'm worried my baby isn't growing (failure to thrive) and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your baby has crossed two or more major percentile lines downward on the growth chart.
  • Mention if your baby seems hungry all the time but is not gaining weight despite frequent feeds.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...
  • Your baby is on a lower percentile but has been growing steadily along their own curve since birth
  • Your baby dropped from a higher percentile to a lower one in the first 6 months and then stabilized, which often reflects finding their genetic growth pattern
  • Your baby's weight dipped slightly during an illness but bounced back within a week or two
  • Both parents are small in stature, and your baby is tracking along a lower percentile consistently
Mention at your next visit when...
  • Your baby has crossed two or more major percentile lines downward on the growth chart
  • Your baby seems hungry all the time but is not gaining weight despite frequent feeds
  • Your baby is significantly lighter or shorter than expected for their age and you are concerned
Act now when...
  • Your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds
  • Your baby has signs of dehydration such as no tears when crying, sunken fontanelle, very few wet diapers, or dry cracked lips

What You Can Do at Home

  • Keep track of when you notice i'm worried my baby isn't growing (failure to thrive) — noting the time of day, duration, and any triggers can help your pediatrician.
  • Remember that your baby is on a lower percentile but has been growing steadily along their own curve since birth — this is generally within the range of normal.
  • At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
  • Offer feeding in a calm, distraction-free environment. Avoid forcing or pressuring your baby to eat.
  • While monitoring at home, seek immediate care if your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds.

Slow Weight Gain in Breastfed Baby

Weight gain patterns vary among babies, and breastfed babies often grow differently than formula-fed babies - they tend to gain more quickly in the first three months and then more slowly from three to twelve months. This is normal and is reflected in the WHO growth charts. However, if your baby is consistently gaining less than expected or has dropped significantly on their growth curve, it is important to work with your pediatrician and possibly a lactation consultant to identify the cause and ensure your baby is getting enough milk.

Baby Not Drinking Enough Milk

Babies naturally vary how much milk they drink from day to day, and a temporary dip in intake is usually nothing to worry about. Common causes include growth pattern changes, distractibility, teething, mild illness, or simply not being as hungry on a particular day. As long as your baby is having plenty of wet diapers and continuing to gain weight along their growth curve, they are likely getting enough.

My Baby Isn't Interested in Food

Many babies show limited interest in food when solids are first introduced, and this is usually perfectly normal. Babies develop at different rates, and some take weeks or even months to become enthusiastic eaters. As long as your baby is still getting adequate milk and growing well, a slow start with food is not a cause for concern.

Signs of Low Milk Supply

Many parents worry about low milk supply, but true low supply is uncommon. The most reliable signs your baby is getting enough milk are: adequate wet and dirty diapers (6+ wet diapers per day after day 5), steady weight gain, and your baby seeming satisfied after most feedings. Breast size, feeling "empty," baby wanting to nurse often, or pumping small amounts are NOT reliable indicators of low supply. If you are concerned, have your baby weighed and talk to a lactation consultant.

Milestone

Milestone Checklists by Age

Track your baby's developmental milestones from birth to 5 years with age-specific checklists.

Guide

Feeding & Nutrition Guide

Complete guide to breastfeeding, formula feeding, and solid food introduction.

Tool

Growth Percentile Calculator

Plot your baby's weight, length, and head circumference on WHO/CDC growth charts.

Milestone

Month-by-Month Development

Detailed monthly development guides from birth through 24 months.

Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is i'm worried my baby isn't growing (failure to thrive) normal?
Failure to thrive, now often called growth faltering, means a baby is not gaining weight or growing as expected. It is important to know that babies naturally shift percentiles in their first two years, and being on a lower percentile is not the same as failure to thrive. True growth faltering involves crossing two or more major percentile lines downward and usually requires medical evaluation to determine the cause.
When should I call the doctor about i'm worried my baby isn't growing (failure to thrive)?
Your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds Your baby has signs of dehydration such as no tears when crying, sunken fontanelle, very few wet diapers, or dry cracked lips
When is i'm worried my baby isn't growing (failure to thrive) normal?
Your baby is on a lower percentile but has been growing steadily along their own curve since birth Your baby dropped from a higher percentile to a lower one in the first 6 months and then stabilized, which often reflects finding their genetic growth pattern Your baby's weight dipped slightly during an illness but bounced back within a week or two
What causes i'm worried my baby isn't growing (failure to thrive)?
Failure to thrive, now often called growth faltering, means a baby is not gaining weight or growing as expected. It is important to know that babies naturally shift percentiles in their first two years, and being on a lower percentile is not the same as failure to thrive. True growth faltering involves crossing two or more major percentile lines downward and usually requires medical evaluation to determine the cause. Common explanations include: Your baby is on a lower percentile but has been growing steadily along their own curve since birth. Your baby dropped from a higher percentile to a lower one in the first 6 months and then stabilized, which often reflects finding their genetic growth pattern.
What should I mention to my pediatrician about i'm worried my baby isn't growing (failure to thrive)?
You should mention i'm worried my baby isn't growing (failure to thrive) at your next visit if: Your baby has crossed two or more major percentile lines downward on the growth chart. Your baby seems hungry all the time but is not gaining weight despite frequent feeds. Your baby is significantly lighter or shorter than expected for their age and you are concerned.
Is i'm worried my baby isn't growing (failure to thrive) normal at 0-3 months?
Weight gain in the first three months is typically rapid, averaging about 5 to 7 ounces per week. After an initial weight loss of up to 7 to 10 percent of birth weight in the first few days, babies should regain their birth weight by 10 to 14 days. If your baby has not regained birth weight by two weeks or is gaining less than 4 ounces per week, your pediatrician will want to evaluate feeding. Common causes at this age include difficulty latching, low milk supply, tongue tie, or formula preparation errors.
Is i'm worried my baby isn't growing (failure to thrive) normal at 3-6 months?
Growth velocity naturally slows slightly at this age but should remain steady. Babies typically gain about 3 to 5 ounces per week. If your baby's weight has crossed two or more major percentile lines on the growth chart, your pediatrician may want to investigate. It is worth noting that breastfed and formula-fed babies have different growth patterns, and the WHO growth charts, which are based primarily on breastfed babies, are recommended for all infants under 2 years.
Should I go to the ER for i'm worried my baby isn't growing (failure to thrive)?
Seek emergency care if your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds, or if your baby has signs of dehydration such as no tears when crying, sunken fontanelle, very few wet diapers, or dry cracked lips. When in doubt, call your pediatrician's after-hours line for guidance.
Does i'm worried my baby isn't growing (failure to thrive) go away on its own?
In many cases, i'm worried my baby isn't growing (failure to thrive) resolves on its own, especially when your baby is on a lower percentile but has been growing steadily along their own curve since birth. By 12-24 months, toddlers grow more slowly than infants, and their weight gain may only be 3 to 5 pounds over the entire second year of life. Picky eating is very common at this age and can make parents anxious about growth, but most picky toddlers grow fine. If your toddler has dropped significantly on their growth curve, your pediatrician will likely evaluate their diet, look for underlying conditions, and may refer you to a pediatric nutritionist. The goal is to identify whether the issue is insufficient intake, increased caloric needs, or poor absorption.
AAPWHOCDC

References

  1. [1]American Academy of Pediatrics. Failure to Thrive. Pediatrics in Review. AAP
  2. [2]World Health Organization. WHO Child Growth Standards. WHO
  3. [3]Centers for Disease Control and Prevention. Growth Chart Training: Using the WHO Growth Charts. CDC

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss I'm Worried My Baby Isn't Growing (Failure to Thrive).

Things to mention

  • Describe when you first noticed i'm worried my baby isn't growing (failure to thrive) and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your baby has crossed two or more major percentile lines downward on the growth chart.
  • Mention if your baby seems hungry all the time but is not gaining weight despite frequent feeds.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

  • Your baby has crossed two or more major percentile lines downward on the growth chart
  • Your baby seems hungry all the time but is not gaining weight despite frequent feeds
  • Your baby is significantly lighter or shorter than expected for their age and you are concerned

Urgent signs to report immediately

  • Your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds
  • Your baby has signs of dehydration such as no tears when crying, sunken fontanelle, very few wet diapers, or dry cracked lips

My notes

From ismybabyalright.com — free, evidence-based baby health guides

All content follows our editorial policy and is reviewed against published clinical guidelines.

2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members

Related Resources

Food Introduction GuideFeeding & Pumping GuideBaby Meal PlannerMilestone ChecklistsEarly Intervention DirectoryGrowth Spurts TimelineGrowth Percentile CalculatorBaby Sign Language GuideBaby Tracker

Bottom line

Most cases of i'm worried my baby isn't growing (failure to thrive) are normal. Talk to your pediatrician if your baby is losing weight, appears listless or excessively sleepy, and is difficult to wake for feeds.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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Related Feeding Concerns

Slow Weight Gain in Breastfed Baby

Weight gain patterns vary among babies, and breastfed babies often grow differently than formula-fed babies - they tend to gain more quickly in the first three months and then more slowly from three to twelve months. This is normal and is reflected in the WHO growth charts. However, if your baby is consistently gaining less than expected or has dropped significantly on their growth curve, it is important to work with your pediatrician and possibly a lactation consultant to identify the cause and ensure your baby is getting enough milk.

Baby Not Drinking Enough Milk

Babies naturally vary how much milk they drink from day to day, and a temporary dip in intake is usually nothing to worry about. Common causes include growth pattern changes, distractibility, teething, mild illness, or simply not being as hungry on a particular day. As long as your baby is having plenty of wet diapers and continuing to gain weight along their growth curve, they are likely getting enough.

My Baby Isn't Interested in Food

Many babies show limited interest in food when solids are first introduced, and this is usually perfectly normal. Babies develop at different rates, and some take weeks or even months to become enthusiastic eaters. As long as your baby is still getting adequate milk and growing well, a slow start with food is not a cause for concern.

Signs of Low Milk Supply

Many parents worry about low milk supply, but true low supply is uncommon. The most reliable signs your baby is getting enough milk are: adequate wet and dirty diapers (6+ wet diapers per day after day 5), steady weight gain, and your baby seeming satisfied after most feedings. Breast size, feeling "empty," baby wanting to nurse often, or pumping small amounts are NOT reliable indicators of low supply. If you are concerned, have your baby weighed and talk to a lactation consultant.

Toddler Picky Eating

Picky eating is one of the most common and normal behaviors in toddlers, peaking between ages 2 and 3. It is a developmentally appropriate way for toddlers to assert independence and learn about their world. Most picky eaters grow out of it and end up with a varied diet by school age, especially when parents continue to offer foods without pressure.

Baby Reflux / GERD

Gastroesophageal reflux is very common in babies because the valve at the top of the stomach is still maturing. Most infant reflux is uncomplicated, meaning your baby spits up but is otherwise happy and growing well. True GERD, where reflux causes pain, feeding difficulties, or poor weight gain, affects a smaller number of babies and is very treatable.