SymptomChildren's health
Failure to Thrive: Signs Your Child Is Not Growing as Expected
Failure to thrive describes a baby or young child who is not gaining weight, and sometimes length, as expected for their age. Parents usually notice clothes still fitting for months, a child who seems thin, or a doctor pointing out that weight has dropped across lines on the growth chart. The most common reason is simply not taking in enough calories, often from feeding difficulties. Less often, a medical problem causes poor absorption or extra energy needs. Most children catch up once the cause is found.
Also called: Poor weight gain, faltering growth, weight faltering, slow weight gain in infants, FTT
At a glance
- What it means
- Weight gain that is slower than expected, shown as falling across growth chart lines.
- Signs
- Thin limbs, little weight gain between checkups, fewer wet diapers, low energy, delayed milestones.
- Common causes
- Feeding difficulties, breastfeeding problems, reflux, milk allergy, too much juice, picky eating.
- Medical causes
- Celiac disease, cystic fibrosis, heart or kidney problems, infections, hormone problems.
- What to do
- See your pediatrician; bring a 3-day feeding diary.
When to get help
Call 911 or go to the ER
- A baby who is floppy, very drowsy, hard to wake or not feeding at all
- A baby with forceful (projectile) vomiting after every feed and fewer wet diapers (possible pyloric stenosis)
- Signs of dehydration: no wet diaper for 6 to 8 hours, a sunken soft spot, no tears, dry mouth
- Fast or labored breathing, blue lips, or sweating during feeds
See a doctor within a day or two
- A newborn still below birth weight after 2 weeks
- A baby who is feeding poorly and has fewer than 6 wet diapers a day after the first week
- Persistent vomiting, bloody stools or diarrhea lasting more than a week
- Weight loss in an infant or toddler
Book a routine appointment
- Weight that has dropped across two or more major lines on the growth chart
- A child who looks thin, is often tired, or is behind on milestones
- Feeding battles, gagging on solids, or very limited foods eaten
- Repeated chest infections, oily or very smelly stools, or a swollen belly
What failure to thrive looks like
Failure to thrive is not a disease but a sign that a child is not getting, keeping or using enough calories. Doctors notice it on the growth chart. Parents may notice:
- weight that stalls: the same clothes and diaper size for months
- thin arms, legs and buttocks, with loose skin folds
- fewer wet diapers or infrequent bowel movements
- low energy, sleepiness or irritability, or a baby who is unusually quiet
- delayed milestones such as rolling, sitting, crawling or talking
- feeding that takes a very long time, or a baby who tires during feeds
- in older babies, length and head growth slowing after weight has slowed
Newborns normally lose up to about 7 to 10 percent of birth weight in the first days and regain it by 10 to 14 days. After that, babies typically gain about 150 to 200 g (5 to 7 oz) a week for the first few months.
Is it failure to thrive or just a small child?
Many children are small but healthy. The key is the pattern:
| Healthy small child | Possible failure to thrive |
|---|---|
| Tracks steadily along a low line on the chart | Drops across two or more major percentile lines |
| Small parents | Was larger, then slowed down |
| Normal energy and development | Tired, irritable or delayed |
| Weight and length in proportion | Weight much lower than length suggests |
Breastfed babies often gain a little more slowly than formula-fed babies after 3 to 4 months, which is normal. Doctors use WHO growth charts for children under 2.
Common causes
Not taking in enough calories
This is the cause in most children:
- breastfeeding difficulties: poor latch, low milk supply, tongue-tie, very short or infrequent feeds. See breastfeeding problems.
- formula made up incorrectly, especially watered down
- too much juice or milk in toddlers, filling them up instead of food
- feeding difficulties: slow, uncoordinated sucking, gagging on textures, feeding aversion after painful reflux, or very selective eating
- household stresses: food insecurity, parental illness or postpartum depression, chaotic mealtimes. These are common and are discussed without blame.
Losing calories
- Gastroesophageal reflux with frequent vomiting
- Pyloric stenosis: projectile vomiting at 2 to 8 weeks of age
- Cow's milk allergy: vomiting, diarrhea, blood or mucus in stool, eczema
- Celiac disease after gluten is introduced: diarrhea, swollen belly, irritability
- Cystic fibrosis: oily, foul-smelling stools, chest infections, salty skin
Using up extra calories
- Congenital heart defects: sweating and breathlessness during feeds
- Chronic lung disease, chronic infections (including urinary infections) and an overactive thyroid
What happens at the doctor's office
Your pediatrician will plot weight, length and head size, review the pregnancy and birth, and ask in detail about feeding. Bringing a 3-day diary of everything your child eats and drinks, including amounts, plus diapers and stools, is extremely useful. They may watch a breastfeed or bottle feed or a meal.
Most children need only a few simple tests, if any: a urine test and basic blood tests. More specific tests are added if symptoms point to a cause. See failure to thrive for how it is diagnosed and treated.
What parents can do now
- Offer feeds often: newborns at least 8 to 12 times in 24 hours.
- For toddlers, offer 3 meals and 2 to 3 snacks at regular times; limit milk to about 16 to 24 oz (500 to 700 ml) a day and avoid juice.
- Add calories without adding volume: butter, oil, cheese, full-fat yogurt, nut butters (when age-appropriate).
- Keep mealtimes calm and free from screens; avoid pressuring or force-feeding.
- Ask for help: lactation consultants, feeding therapists and community nutrition programs can make a big difference.
Frequently asked questions
What are the signs of failure to thrive?
The main sign is weight gain that is slower than expected, seen as falling across lines on the growth chart. Others include thin limbs, fewer wet diapers, low energy, irritability, slow feeds and delayed milestones. In longer-standing cases, length and head growth also slow.
Why is my baby not gaining weight?
The most common reason is not getting enough milk, from latch or supply problems, short feeds or formula mixed incorrectly. Reflux with frequent vomiting, milk allergy, and less often heart, gut or genetic conditions can also cause it. A pediatrician can check weight and feeding.
Is failure to thrive the parents' fault?
Usually not. Most cases come from feeding difficulties, medical problems, or circumstances such as limited money or a parent's illness. Doctors focus on solving the problem together. Only rarely is neglect involved, and help is available in every case.
Can failure to thrive be reversed?
Yes. Most children catch up in weight once the cause is treated and calorie intake improves. Early treatment matters, because long periods of poor nutrition in the first 2 years can affect growth and development. Regular follow-up tracks progress.
How much weight should a baby gain each week?
In the first 3 months, babies usually gain about 150 to 200 g (5 to 7 oz) a week, slowing after that. Babies typically double their birth weight by about 4 to 5 months and triple it by 1 year. Steady growth along a curve matters more than exact numbers.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Pediatrics (HealthyChildren.org): Failure to Thrive
- American Academy of Family Physicians: Failure to Thrive - A Practical Guide
- NICE: Faltering growth - recognition and management (NG75)
- MedlinePlus: Failure to thrive
- CDC: WHO Growth Standards for children 0 to 2 years