Possible Causes of Failure to Thrive

What are some possible causes of the very general diagnosis of “failure to thrive”? At 7 weeks, our daughter is still 7.5 ozs below her birth weight and none of the “experiments” our doctor has tried have helped her to gain any weight consistently. We were advised to try eliminating all dairy products from my diet, then supplementing formula after each breastfeed, and now give up nursing entirely and formula feed, but none of these is making a difference. I might also note that she began life with very loose, mucousey stools while nursing, and now has quite firm, round, rubbery stools with the formula..neither of which seems normal in my experience. Further, she is more fussy since we switched to the formula only routine; she is not as contented as she was previously and cries out in her sleep.
Angela Quinn – Tipp City, Ohio

Possible Causes of Failure to Thrive

Dr. Greene’s Answer:

When I see a new baby in my office for her first visit, her parents often get more excited about finding out their child’s weight than just about anything else. The scale becomes the focus of the visit. “Is my baby growing okay?” is an urgent question for parents until they are sure of the answer. This deeply rooted concern makes sense.

Growth is central to childhood. In fact, an organism is considered “a child” during that period of its life in which it is growing.

Growth is particularly noticeable and rapid during the beginnings of life. In the first four to six months, a baby typically doubles her birth weight. She will triple her birth weight by the time she is a year old. Maximal brain growth also occurs during the first six months of life. The brain grows as much during a child’s first year as it will during the entire rest of her life.

A child is failing to thrive when she is not growing at the expected rate for her age, or if her weight is disproportionately low compared to her height and head circumference.

A simplistic but very useful way to look at growth failure is to consider that in order to grow, a child must take in adequate calories, absorb those calories, and use them for growth.

If a child is not growing well, first consider whether she is actually taking in an adequate number of calories (and other nutrients). What is she being fed? How much is offered and how often? How much does she actually take? Is she able to suck and swallow adequately? Most cases of failure to thrive in infants can be solved by carefully addressing these questions. It sounds as if this is what your pediatrician is focusing on.

If caloric and other nutrient intake is adequate, consider whether the calories are continuing down the gastrointestinal tract, being digested, and being absorbed into the body. Sometimes the food is vomited back up either due to a blockage in the gastrointestinal tract or a condition called gastroesophageal reflux, in which food travels backwards from the stomach to the esophagus. Sometimes the calories make it through the stomach, but are not absorbed — they are lost out the other end — either because of diarrhea or because of an inability to absorb the nutrients. Possible underlying causes for this include viral, bacterial, or parasitic infection, a digestive enzyme deficiency, a genetic disease (such as cystic fibrosis), or a milk protein intolerance.

When adequate calories are consumed and absorbed into the body, the calories could be spilling out in the urine, if the kidneys are not effective at holding in the protein. If the fuel remains safely in the body, the body could still be burning it at a faster-than-normal rate, leaving insufficient calories for growth. Possible causes of this hyper-metabolic state include hyperthyroidism, chronic infection, congenital heart disease, or malignancy.

Some children will even fail to thrive in the face of adequate calorie absorption simply from extreme neglect. Kids who are not hugged, held, and cared for don’t grow. This has been clearly demonstrated in orphanages where the adult-child ratio is very low. Even if these children are being well nourished, they often fail to thrive, simply because they lack personal care.

So, as you can see, growth requires the smooth working together of many systems throughout the body. The specific causes of failure to thrive are quite numerous, with problems in every major organ system represented. The most common causes for failure to thrive vary with age. In the first three months of life feeding difficulties, infections, gastroesophageal reflux, inborn errors of metabolism, cystic fibrosis, and milk-protein intolerance top the list. Simply switching to formula is not a sufficient solution if your child doesn’t respond with steady growth.

Many infants regain their birth weights by one week of age. Most regain their birth weights by two weeks of age and have a steady weight gain thereafter. A child who has gone seven weeks without regaining her birth weight deserves a thorough work-up to determine the cause. This work-up should begin with a detailed feeding history and a careful physical examination. If the cause for failure to thrive is not apparent, the next step would be to run some simple screening lab tests including a Complete Blood Count (CBC) with differential, urinalysis, and a measurement of serum electrolytes, BUN and creatinine.

Given your child’s unusual stools, it might be useful to have the stool examined for evidence of a malabsorption syndrome. If all of these studies come back normal, and your daughter is still not growing, then a further round of tests, possibly including thyroid function tests, liver enzymes, ammonia, lactate, pyruvate, a sweat chloride test, urine organic acids and serum amino acids, and perhaps x-ray studies, would be indicated.

If a cause is still not found, your doctor will be able to direct you to an appropriate specialist for further testing based on your daughter’s symptoms, test results, and physical exam findings.

Every mom wants to make sure that her child is growing. This instinct runs strong and deep and is there for good reason. When growth is not proceeding apace, take steps to correct the problem or to discover its cause.

Dr. Alan Greene

Dr. Greene is the founder of DrGreene.com (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

  1. Nero

    My daughter is going to 6 month now and is not gaining weight, is unable to feed through the mouth.she was diagnosed of microcephy at birth and miconuim.my doctor seems not to tell me any thing about inability to feed if its a thyroid problems or not and what is the way out.

  2. Ellie Cooper

    My Granddaughter is almost 2 weeks old . She weighted at birth 5 lbs 12oz. She has lost 11oz. The doctors are worried because she is losing weight. She was born 3 weeks early.Any helpful answers. Pls help. Ty

  3. Lee

    Please help. Baby not gaining weight. Born c-section at 38 weeks. 4.07kg. Drinking badly from start. Tried breast feeding. Would not latch cried a lot. Week 2 started crying 14 hours a day. Called pediatric went to hospital fed him nan ha. Then neocate, no difference tube fed, cried less gained 200 grams in 4 days left hospital, no weight gain. They cut under his tongue, made drinking better use to drink only 10-20 ml now on 60 ml if we are lucky back on nan ha. Drinks every 3 hours. Dr says its sensory I don’t believe it. Tested all organs/ reflux drank barium no luck. Went to see chirp/ occupation therapist and speech therapist. Still no weight gain 6 weeks old now 4.9 kg since birth. Tried different bottles and teets. What am I missing. Going out of my mind. In South Africa. Hope you can help. Who do I see next. A dietician??? Help. When you give Colin drops or panado makes no difference sounds like person who is hungry the way it drops into the stomach. Nexium no difference spits up slimy milk no just milk.

  4. Jada

    Hi doctor,

    I have an 11 1/2 month old son who currently weighs 18 lbs; birth weight was 7 lbs 14 oz. Should I be concerned about his weight? He is tiny but his Pediatrician seems like it’s not a concern even though he’s dropped on his growth chart. Not sure if maybe we need a second opinion.

  5. naz

    Dear doctor,

    my daughter weighed 5lb 1oz when she was born and failed to grow adequately due to a vsd…

    she had a vsd repair done at 3.5months…however she is still not growing well enough…she is now 5.5months and weighs 9lb 7oz…HV has referred to dietician and I have been advised to start o solids and higher calorie milk….

    what could be the cause of her failure to thrive…

    a very worried mum


    • kathy

      Hiprobiotimy daughter was also diagnosed with failure to thrive . But after I changed her diet with all organic and GMO free my.daughter has gained weight. Also, I give her raw probiotics.

  6. Jolie

    My son was born with normal weight of 3.3kgs however at week 4 he has lost to 3.1kgs. Doctor said it was failure to thrive and advised me to feed the baby. I am feeding the baby but he’s not gaining weight.

    What can I do to make sure he gains weight?


  7. Adam

    I have a 3 month old son. He eats every 3 hours. Sometimes, actually often, he fights eating. He is breastfeeding. He weighs 9 pounds and 10 ounces. He was delivered via an emergency c section do to meconium. At birth, he weighed 6 pounds and 4 ounces. He is in the lower 5 percentile for weight, but in the 25 percentile in head circumference. With all that said, he is very alert and engaged. He smiles. He follows sounds. He recognizes voices. He sleeps.

    In out most recent visit to the Ear Nose and Throat specialist, she confirmed (through a scope) our pediatrician’s diagnosis of reflux.

    We have been giving him the reflux medicine, but it’s not working. As I stated before, feeding is a challenge.

    I Google a lot. There are so many ominous things out there. Could this be failure to thrive? Am I missing something?

    • Lisa

      Has anyone examined your baby’s mouth for a lip or tongue tie?
      This can also be the cause of slow weight gain and symptoms of reflux.

  8. lacie

    My baby hasn’t gained any weight in a month and she just now turned three months old what should I do.

  9. Natasha

    Can you please recommend any advice?
    Thank you,
    A very frustrated and concerned Omie

  10. Goldie Byerly

    I am working with Early intervention 0 to 3 yrs all and i am interesting in all topics regarding this age range. thank you

  11. shruti

    i have one concern . my daughter is 1 yr 4 months now. she is underweight with only 7.9 kg.
    though she is quite active and playful .she doesnt gain much in weight like in last 4 months she gained only 200gms. Should we worry about her weight ?


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