Is my breastfed baby failure to thrive? Or just not gaining weight?

Why is my breastfed baby not gaining weight?

Sometimes, a breastfed baby will gain weight more slowly than you, or others, think they should. It might be because you aren’t making enough milk, but there are also many other causes of slow weight gain, or the more worrisome, failure to thrive.


Let’s look at common misconceptions, work our way through weight gain troubleshooting, and on into true emergencies.

1. Babies need to nurse very frequently, not every three hours.

Newborns have a one-hour feed-sleep-wake cycle. Humans are a species that carries their babies and keeps them close. Brain development is the most important task of a 0-2 year old. By age two, their brains are 80% the size of adults. Breastfeeding provides special sugars to nourish the brain and near-constant interaction with parents stimulates the creation of the billions of neurons.

2. Babies do not need a lot of food on the first two days of life.

Babies do not need supplementing in the first two days, except in unusual circumstance. It is estimated that women make 15 ml of colostrum a day. That is normal!

Your baby is not starving, they are scared. They need to be constantly skin-to-skin with you and their dad to orient them to love and protection in the world outside the womb. They need to nurse every hour or two and eat a few drops of colostrum.

Colostrum is produced in very small, extremely dense quantities for a reason. It’s the sourdough starter of the baby’s biome. It seeds the intestines with immune factors, prebiotics and probiotics. Transitional milk continues the process, providing more sugars for biome growth. Mature milk delivers the exact food for the dramatic rumbling, gassy, farty process of a healthy, newborn biome. Germs don’t have a chance when facing the fighting powers of a healthy intestinal biome.

Feeding formula disrupts the creation of the biome.

3. It’s normal for breastfed babies to gain weight differently than formula fed babies.

It is normal for exclusively breastfed babies to gain differently than formula fed babies. Because of this, there are different growth charts published for formula fed babies. But, insufficient weight gain should be treated as a red flag, and not a feature of breastfeeding.

4. Mothers don’t have to eat a lot of specific foods or drink a gallon of water a day to make enough milk.

Mothers living through famines are able to adequately nourish and nurture their babies. Your body will adapt and become more efficient to conserve calories, if needed. Your milk will continue to flow on demand. It is a good idea to eat a balanced diet of whole foods so that you feel content and nourished.

5. All human milk is not the same.

Human milk varies from feed to feed, with the baby ‘telling’ the breast how much milk, and in what composition, they need in any particular feed. As the baby develops, your milk changes. Over time, the ratio of sugar and water decreases and protein increases. Fat will always vary from mother to mother, beginning to end of feed, and from feed-to feed.

We know from studying human milk:

  • Milk is an ever-changing living food. It is cornucopia of food, immune factors and pre- and probitics.
  • Boy babies receive higher calorie and more milk by volume, than girl babies.
  • Individual breasts make personalized milk for each twin, even when the twins switch sides.
  • No two samples of milk are the same. 

6. Every baby requires close monitoring until they are gaining weight predictably.

This is normal breastfeeding: A full term, healthy baby, unaffected by birth meds, has unlimited access to their mom’s breast. Their mom is healthy, of normal postpartum weight, and has discomfort, but not pain from breastfeeding, birth or surgery. She makes sure her baby nurses at least 12 times every 24 hours.

Babies nurse in three stages. 

The first stage is the letdown, also called a “milk ejection response”. At this stage you can see milk dripping or spraying out of your nipple. An important point about the letdown? Some people feel it and some people don’t, but everyone has it. During the first few months, your breasts make milk continuously and store it between feeds. As the milk waits for release, fat rises to the top, much like you see in stored expressed milk. As baby suckles gently in a suck-suck-suck pattern, your breast muscle contracts and releases stored milk. A letdown helps your baby eat without effort. It fills them quickly so they have good energy to continue through the second stage of nursing.

The second stage is active nursing. As your milk reserves begin to drain, your baby starts actively ‘milking’ your breast by massaging and compressing your breast with their hands, tongue and lips. During this stage, you should see your baby’s jaw lifting and rolling. You will see or hear a suck-swallow-suck-swallow pattern. You should see jaw movement all the way back by their ear. This action moves the floating fattier milk down and out of your breast. It also stimulates your breast to synthesize more milk. Active nursing becomes the way your baby gets most of their milk after 3 or 4 months, so it’s important to control oversupply in the early months, so your baby learns to actively milk your breast.

The third stage is nurturing. As your baby feels full, their suckling slows. The slow sucking calms them just like a pacifier would. They suck-suck-suck-suck-swallow. This milk is rich in fat. And just like in adult diets, fat has a lot of calories and packs on the pounds. This rich, creamy milk is as enjoyable for your baby as an ice cream cone is for adults. Even if you do not like ice cream, you can understand the comparison.

Normal babies are programmed to initiate breastfeeding and to end feeding when they are full. Babies who are exclusively breastfed are more likely to be normal weight when they are adults.

So, why is my breastfed baby not gaining weight?

When you and your baby have risk factors, slow weight gain is common.

Preterm and prematurity, c-section birth, rapid birth, mother-baby separation, hypoglycemia, sleepiness, jaundice are common risk factors in the baby.

Risk factors for mother are separation from her baby, suffering from birth or medical trauma, being undernourished or with high BMI, experiencing body, breast and nipple pain, a history of anxiety or depression, ignorance and bad advice from her medical team.

In addition, any number of other illnesses and conditions can interfere with normal breastfeeding and result in a baby not gaining weight. A good lactation consultant will assess for risk factors and make appropriate referrals to specialists who can address each issue individually so that breastfeeding works and baby gains weight. Make an appointment with one as soon as you realize there is a problem.

You may ask, “How can I help my breastfed baby gain weight?”

Here are three tips for increasing your baby’s weight gain while breastfeeding:

1. Use hand expression and breast compression before, during and between feeds. Breast compression helps in a few ways. It helps to drain your milk while your baby is nursing. It makes it easier for baby to eat and signals your body to make milk. A new baby often needs some practice to efficiently breastfeed and compressing milk down to your nipple increases how much they eat. It helps a baby who has challenges breastfeeding, due to tongue tie, for example, to have good feeds every time. Hand expression is a low tech and friendly way to collect your milk. When you hand express between feeds, feed your baby all the milk by cup, spoon or bottle. These help a sleepy baby, or a mother who is having nipple pain.

2. If you have low or slow production, switch sides frequently so your baby recieves many letdown bursts. As they suck-swallow, they stimulate your body to make the fattier milk that is made during nursing.

2. If you have abundant milk, bring your baby back to the same breast after they self-detach for a break. Instead of switching sides, return to the same breast for more of your fatty milk. This will help calm your milk production.

3. Feeding frequently, about 12 times a day, means higher fat content in your milk. When your breasts are kept soft between feeds, your baby receives fattier milk. When your breasts fill up, your milk is higher in sugar and protein and lower in fat. It has fewer calories by volume.

Some breastfed babies are fatter than others.

Breastfed babies, like all people, come in all shapes and sizes. Some are lean and some are roly-poly. Fatter babies have more fat to carry them through illness or famine but it does not appear that being either a fat or a lean breastfed baby has any long term health benefits.

The biggest predictor for being a chubby baby appears to be how frequently one is fed. Babies who are frequently fed tend to gain well.

Another factor is how much fat a mother’s milk contains. If your diet is deficient it is possible to increase the fat content of your milk, but mostly, your milk is how it is. Some moms have low fat milk and some moms have higher percentage of fat in their milk.

Lastly, it’s not just how much fat your milk has, but how much fat your baby is getting. If you have an abundant supply and still feel full after your baby nurses, they may not be getting enough fat. If it hurts when they nurse, you may be cutting sessions short. If a baby does not suckle efficiently, they may not be getting enough milk and therefore, enough fat.

The two signs of adequate fat in your milk are lots of mustardy yellow poopy diapers and a chubby baby. A baby up to two months will have four full diapers a day and one or more very large stools a day is common in older babies. A baby who is eating solids will have yellow-brown colored poop.

Managing poor weight gain in your exclusively breastfed infant.

If you have been trying these tips for two or three days with a less than two-week old baby, or 2-3 weeks in an older baby, it’s time to contact an International Board Certified Lactation Consultant (IBCLC). 

Continued poor weight gain in your breastfed infant is either because you aren’t making enough milk or your baby can’t transfer milk very well from your breast to their stomach. Or both.

It might also be that you, or the baby, has a medical problem. An IBCLC can help sort out which problem you should address first, and is able to help you preserve however much breastfeeding you are currently doing. Your baby’s pediatrician should evaluate poor weight gain by looking for issues with milk transfer, neurological, digestive or pathological problems. BUT THEY PROBABLY WON’T. It’s up to you to find help and an IBCLC will be able to screen for problems and find you providers who can help you.

Your primary care, midwife, or OB/GYN are a good resource to learn if your hormonal levels are adequate. Thyroid levels and pre-diabetes, insufficient glandular tissue, PCOS, insufficient hormone levels are all fairly common. Hormone levels impact how much milk you can make, even when you are breastfeeding frequently enough.

Slow Weight Gain Following Early Good Weight Gain

If your baby is breastfed and was gaining along their curve, but now is not gaining appropriately, or worse, clearly falling off their growth curve, I highly recommend working with a Lactation Consultant. The most common reasons for this are, not feeding enough times each day, a baby who can’t milk your breast very well, and hormonal birth control. There are other reasons in addition to these, including mother or baby illness, food sensitivities and even pregnancy.

Failure to thrive is the most extreme form of slow weight gain.

The term itself, is frightening for parents to hear. Many moms feel a condemnation of their feeding choices, even though its definition is “restricted growth in weight and length in an infant or toddler, with unspecified cause.”

FTT is defined as weight consistently below the 3rd to 5th percentile for age and sex, or a decrease in weight to below the 3rd to 5th percentile, or a decrease in the percentile rank of 2 major growth parameters (height, weight or head circumference) in a short period.

There are three reasons (with many root causes) why babies have failure to thrive: 

1. Not taking in enough milk

2. Not absorbing nutrients in milk

3. Burning too many calories

Failure to thrive has many causes, signs to watch for, and of course, treatments.

Because most people assume lack of food is the cause of failure to thrive, let’s start there. 

Problems with breastfeeding (or starting solids in an older infant) can cause failure to thrive. If a baby is not eating well, their family and medical team has to look for possible reasons. Is there a tongue tie, allergy, or restricted feeding? All of the previous breastfeeding suggestions should be looked at again. Frequent eating of age-appropriate foods is vital to children’s good weight gain and health. 

In newborns, damage to the brain or central nervous system may cause feeding difficulties.

Heart or lung problems can affect how nutrients are processed through the body. Anemia or other blood disorders and gastrointestinal problems make it hard to absorb nutrients and/or cause a lack of digestive enzymes needed to digest milk. Because a baby has a short medical history, it may take parents and doctors some time to learn of these. The one visible symptom is slow weight gain, but detective work is needed to find the underlying cause or causes.

What causes failure to thrive in breastfed babies?

When baby is breastfeeding well (more than 10-12 times a day) yet not gaining, failure to thrive may be due to medical problems. Some babies have gastrointestinal problems where it is difficult to absorb nutrients. Some have a lack of important digestive enzymes, or a rare metabolic disorder like Galactosemia. Long-term infections may be present. Eczema and reflux might be other signs present in failure to thrive. Again, these are the symptoms and more testing is needed to find the root cause.

There can also be factors in the child’s environment, such as abuse or neglect by a parent or caregiver, that need to be explored. 

It could be poverty, lack of knowledge, and family stress. Parents can have harmful childrearing beliefs like feeding every four hours, fad diets, or rigid child-rearing regimens. There can be trauma or drug use resulting in neglect. A baby that doesn’t feel well physically or emotionally, can have feeding resistance.

Some families have trouble affording enough food for their children.

When a family can’t afford food, successful breastfeeding is going to help reduce those costs. In the US, there are two government programs, WIC and SNAP, which are resources to help families buy groceries, including formula. Local food pantries and hunger initiatives are also a resource that can help. But the hard truth is that 1 in 5 children in America goes hungry regularly. And if you are that baby or child, you learn ways to “not eat” and these mal-adaptions can turn into failure to thrive.

Case Study: Failure to thrive in a partially breastfed baby

I experienced a case with a client whose baby was underweight nearly from the start. He was born, of average weight, an in an unmedicated, very fast birth to a first time mother who had hyperemesis gravidarum during the entire pregnancy.  He lost more than 10% of his weight in the hospital and was supplemented in order to be discharged. I saw him on the third day after birth.

His mother had a strong desire to breastfeed, even though it was painful to breastfeed in the beginning. I noted a possible tongue tie, and referred the parents to a chiropractor and a pediatric dentist for evaluation. The parents declined, and over time, the pain decreased. The baby was colicky and developed eczema during his first month. The mother, already vegetarian, adopted a soy-free vegan diet. She saw some improvement and a decrease in crying and gas, but the baby’s weight still hovered in the 10th percentile, which seemed off, because the mother is average size, and the father is tall and lean, but not skinny.

She increased the amount of fat, grains and vegetables in her diet and eliminated nuts. With this change, the baby seemed the happiest he had been. She returned to work and pumped, leaving bottles of her milk to feed the baby. The father sometimes fed the breastmilk, and sometimes fed formula, in an effort to “fatten him up.”  The parents did not agree on this. And notably, the baby was inconsolable and clearly in pain after drinking formula.

The mother contacted me at about 4 months postpartum. She was suddenly unable to pump more than 1/2 oz. We worked though the usual pumping troubleshooting, and as a last resort, I asked if she could be pregnant? Maybe she was? She took a pregnancy test which confirmed it.

Because of the history of colic and eczema, she started feeding different hypo-allergenic formulas, and continued breastfeeding with a very low supply. She started him on a soy-free formula. The baby was still very fussy, still had eczema, and was still not gaining very much weight. He had started seeing a gastroenterologist as well. She gradually increased the amount of formula until he was drinking 80 oz per day. But even at this extreme amount, he was not gaining. His poop was explosive and smelled terrible.  

The baby was now nearly 5 months old, and the gastroenterologist recommended reducing the amount of formula and giving pureed food. By 7 months, he was eating a good amount of “tolerated” table foods and 32 oz of hypo-allergenic formula, per day. The eczema was under control and his behavior was generally normal. By nine months, he was in the 50th percentile for weight and 95th for height. 

Case Study: Failure to Thrive in a 4-Month-Old Nursing Infant 

Another mother came to me because her baby had dropped from the 50th percentile to the 5th percentile between her two and four month well-baby check ups. On the intake form, she noted that her baby was breastfeeding 5 times a day and zero times at night. In normal babies, breastfeeding occurs every 1 to 3 hours for a total of 8-12 times every 24 hours. When I asked if her baby slept through the night, or asked to feed, she said that she had been following the BabyWise program. We double-checked the program which showed that a 4 month old baby should feed 7 times in 24 hours. I recommended that she carefully consider her options if she wanted her baby to gain weight. She could increase breastfeeding sessions and maybe lose sleep, or continue on while her daughter lost more weight.

For the next week, the mother kept her baby near her, and nursed nearly every hour. She called after two days to say that her milk was more plentiful and her baby had been able to nurse 10 times that day. The baby seemed more content and had not used the pacifier. The baby was still sleeping through the night, but she said that if her daughter woke, she would nurse her then, as well.

The mother purchased a baby scale. She reported that in the first week, her baby had gained eight ounces. After a month, she had gained more than three pounds and they were breastfeeding between 10 and 12 times a day.

Failure to thrive resulting in death is uncommon

You will find scary articles when you search ‘failure to thrive’ with headlines like: “My breast milk caused my baby’s failure to thrive.” and “Just one bottle would have saved my baby’s life.”

When you read enough of these stories, there are common red flags that go unheeded by parents, lactation consultants, pediatricians, and nurses, in their pursuit of exclusive breastfeeding.

  • Breastfeeds all the time – with a “quick feed” being 45- 90 minutes
  • Screaming and thrashing in discomfort 
  • Falls asleep at breast, after a few sucks
  • Only getting enough milk to survive, even though constantly feeding
  • Cycle of feeding and screaming, and clearly in pain
  • Sleeps all the time, can’t rouse even to eat

Breastfeeding is one way to feed your baby, but if your baby is showing any of these symptoms, you need to add a supplement while you figure out why breastfeeding is not working.

A supplement doesn’t automatically mean formula.

If you can pump or express milk, do it and spoon feed, cup feed, finger feed or bottle feed your supplemental milk. If you can buy milk from a licensed milk bank, or receive milk from a trusted donor, that is also a supplement. And if these aren’t available, we are fortunate to have good formulas, because breast milk doesn’t always appear at the drop of a hat. 

Problem-Solving Formula for Failure to Thrive in a Breast-fed Baby

Remember the three reasons why babies do not gain weight: 

1. Not taking in enough milk

2. Not absorbing nutrients in milk

3. Burning too many calories

Failure to thrive and insufficient milk are common reasons for early weaning. Mothers often doubt their natural ability to successfully breastfeed a young infant.

There is a lack of well-baby and lactation clinics especially for the first 10-14 days postpartum.

When these are available, professionals and peers provide screening for underlying causes, and reassurance and counseling to mothers. A well baby clinic can provide valuable benchmarks of success or need to supplement. They provide an objective set of eyes for an emotional and subjective client, who finds it hard to believe that she is doing really well or conversely, not doing well and could use support.

Often times, just asking the mother how she feels the feedings are going, will help her to see how things really are, both positively and negatively.

‘Failure to Thrive’ in the Breastfeeding Mother

We also have to keep an eye out for mothers who are failure to thrive. Trauma from birth and lack of sleep, pressure to perform at breastfeeding, mothering, and all too often, returning to work, can lead to postpartum mood disorders and eating disorders. There can be real feelings of worthlessness and a disconnect from her baby, and all that used to bring her joy. It’s important to be aware that this exists and reach out for help, if you are that mother, or know someone who sounds like this.

Treatments include social support from peers and therapists trained in helping new mothers adjust. Basics like good nutrition, gentle exercise, being outdoors and having respite from 24/7 mothering are vital to keep a mother healthy, and to help struggling moms get back on their feet.

Don’t let failure to thrive define your success story

When there is true failure to thrive at the breast, it is unfair to hand over the problem to a feeding bottle and a bottle of Xanax, without a trial with an at-breast, Lact-Aid Supplementer. While not perfect, this tiny feeding tube placed in the corner of a baby’s mouth, while at his mother’s breast can offer a full supply of nutrition for a hungry baby, stimulation to insufficient milk production, and feelings of bonding and nurturing at the breast. This simple device allows anyone who desires, to breastfeed. 

There are many more solutions for failure to thrive and certainly, more than can be covered in a failure to thrive nursing article. If you have questions about slow weight gain, or failure to thrive, call or text me, Donna Bruschi, IBCLC at 845-750-4402

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