Baby Not Gaining Weight: Reasons & 8 Tips To Help Them Gain

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Many parents worry when their baby does not gain weight as expected; however, it is important to understand that the growth rate among babies varies, as does their weight gain pattern.

Healthy newborns lose around 5–10% of their weight within a week of birth (1). However, they regain this weight within two weeks. By 12 months, the birth weight of most babies gets tripled (2). These weight changes indicate healthy growth and optimal calorie consumption in babies.

If your baby does not gain enough weight, there is often no reason to worry. Several benign causes lead to slow weight gain in babies. Consult a pediatrician to understand the exact cause and take steps to prevent any long-term problems.

Read this post to understand the possible reasons a baby does not gain weight, notable signs and symptoms, and the treatment options available.

In This Article

Reasons For A Baby Not Gaining Weight

A baby may be gaining weight slowly or not gaining weight at all. In both cases, several factors can be responsible (3). The following are some of the notable potential reasons.

1. Insufficient calorie intake

Most healthy, full-term newborns take one to two ounces of milk per feeding every two to three hours (4). As they grow, the amount of milk per feed increases, and the feeding frequency reduces, yet babies get the required number of calories. However, some babies may not get the calories they need due to any of the following reasons.

  • Poor latching and positioning of the baby make it difficult for the baby to consume adequate breast milk. Chronic latchingiXInability of the babies to attach or suck milk during breastfeeding  issues can also cause pain and discomfort to the mother, leading to infrequent feedings. These breastfeeding issues can be corrected with the guidance of a lactation consultant.
Poor latching can make it difficult for the baby to consume adequate breast milk

Image: Shutterstock

  • Chronic low milk production is one of the prominent reasons for a baby not gaining weight properly. Low milk supply can happen due to several medical and non-medical reasons, such as infrequent breastfeeding or breast surgery. Consulting a lactation consultant is crucial for prompt resolution of the issues.
  • Short nursing sessions are another common reason for a baby not gaining weight. Nursing sessions become shorter if the mother and the baby face feeding difficulties, such as low milk supply or the baby falls asleep on the breast or while bottle-feeding. Waking a baby up for feeding and keeping them engaged by stroking their cheeks or hands or feet can help them nurse longer.
  • Starting solids can cause slow weight gain as the baby’s body adjusts to the new feeding pattern. Remember, even when babies are eating solids, many of their calories come from breast milk or formula. If the frequency of breast milk or formula feeding reduces while feeding solids, it could lead to slow weight gain.
Quick fact
Babies rapidly gain weight during the initial three months, reaching 30 grams/day. The weight then dips to about 15 grams/day by three to six months and 10 grams/day from six months to one year (15).
It may take some time for the baby's body to adjust

Image: Shutterstock

  • Medical conditions: Certain medical conditions, such as Down’s syndromeiXChromosomal disorder (trisomy 21) characterized by reduced muscle tone, delayed physical and intellectual development and premature birth, cause slow weight gain. These conditions usually cause feeding difficulties due to underdeveloped muscles required to suck and swallow (5).

2. Low absorption of calories

Some babies may be consuming sufficient calories, but the absorption of those calories may not be happening due to (6):

  • GERD: Gastroesophageal reflux disorder is a digestive disorder where the baby unusually and frequently spits up after feeds. The underdeveloped or weak lower esophageal sphincter is the prominent cause of reflux in infants. GERD could impede feeding sessions or interfere with digestion, hindering the absorption of calories.
GERD may cause babies to spit up frequently

Image: Shutterstock

  • Food allergies and sensitivities: Some babies are allergic or sensitive to certain foods. For instance, in celiac disease, an autoimmune disorderiXA group of medical conditions where the body’s immune system erroneously attacks healthy cells , a baby cannot digest wheat. If they consume wheat or wheat-based cereal, they get diarrhea or vomiting, contributing to poor calorie absorption, which could ultimately prevent the baby from gaining weight.

Besides these, medical conditions such as galactosemia and cystic fibrosis can impair the body’s ability to produce energy from food or hinder energy absorption, causing slow or no weight gain.

3. Over-utilization of calories

Babies have increased energy needs due to rapid growth and development. However, in certain conditions, these needs increase further. For instance, babies with breathing difficulties or infections need more calories than usual to heal, recover, and gain weight.

If your baby isn’t gaining weight, irrespective of the cause, consult a pediatrician promptly.

Diagnosis Of Weight Gain Issues In Babies

A pediatrician will do a physical examination, take your infant’s medical history, and check their height and weight to diagnose weight gain issues. They will plot your baby’s height and weight on the pediatric growth chart to determine the growth pattern. A pediatric growth chart is an assessment tool that compares a baby’s weight-for-age and weight-for-length against the standard ranges for babies of the same gender and age (7).

The US Centers for Disease Control and Prevention (CDC) recommends using the WHO’s growth standards chart to monitor breastfeeding infants’ growth (8). For formula-fed babies, using the CDC’s growth chart is advisable.

Your doctor will record your baby’s weight and height on every visit and monitor your baby’s overall growth. If a baby shows persistent low weight gain over a period, they may assess the baby further to determine the cause.

In cases of no weight gain for an extended period, the doctor may advise some tests, such as blood count, thyroid hormone test, and urinalysisiXA series of urine tests employed to diagnose potential health disorders and infections .

How To Help Babies Gain Weight?

You can help babies gain weight in several ways. Discuss a strategy with your pediatrician for the best outcome for your baby.

  • Focus on treating any underlying medical condition, such as a digestive disorder or other illness. Prompt treatment of the condition in most cases can help a baby attain the correct weight. If your doctor sees the need, they may suggest nutritional supplements to fill the dietary gaps.
  • Monitor your baby’s latch. Inverted nipples, tongue-tie, and cleft palateiXA congenital disability where the baby’s palate (roof of the mouth) is abnormally developed  are a few causes of latching failure. If the baby cannot latch properly or you face any issue with the positioning of the baby, promptly consult a lactation consultant.
Quick tip
When a baby looks comfortable while feeding and you hear them swallow milk, it indicates that they have latched appropriately (16).
  • Avoid using pacifiers until feeding is established. It can take three to four weeks for a baby to become adept at breastfeeding or bottle-feeding (9). Offering a pacifier before feeding is established could lead to nipple confusion, leading to inadequate feeding. Even when feeding is established, do not use a pacifier as a temporary aid to calm a hungry and cranky baby. Offer breast or bottle when the baby is hungry and the pacifier when the baby is cranky but not hungry.
  • Keep your baby awake during feeds. An awake and active baby usually nurses for about 20 minutes or more on one or both breasts during each feeding (10). If you feel your baby might fall asleep, tickle their palms and feet, change your breastfeeding position, burp them, or switch the breast to keep them awake.
Try keeping the baby awake for a proper feed

Image: Shutterstock

  • Increase the frequency of feeding to ensure the baby is consuming sufficient breast milk or formula. Frequent breastfeeding is also helpful in boosting milk production. Stay hydrated, eat a well-balanced diet, and rest well to ensure healthy milk production. You may consume some baby-safe lactation-boosting foods, such as fennel and oatmeal, after consulting your lactation consultant.
  • Monitor the baby’s calorie intake by recording their milk consumption using markers on the bottle. You can also closely observe the manner your baby sucks and swallows while feeding. Babies tend to suck slowly and persistently when the milk flow is optimum. Alternatively, you can do a diaper check. A well-fed baby wets six to eight diapers in a day (11).
  • Increase the baby’s calorie intake. To do so, encourage your baby to empty one breast before switching to another. It ensures the baby is getting the hindmilk, containing a higher percentage of fat than foremilk. For formula-fed babies, you can consult a pediatrician to know if a formula change is required.
  • Check about supplementing the feed or using a mixed feed approach. In such cases, the doctor may suggest you feed both breast milk and formula to your baby. If you are formula feeding, you can feed expressed breast milk to your baby through a bottle or any other alternative feeding technique, such as a dropper or with a cup and spoon.
Check about supplementing the feed

Image: Shutterstock

Besides these, weigh your baby regularly at home until they start gaining weight. Maintain a weight record and share the data with your doctor to work closely for your baby’s healthy weight gain.

Frequently Asked Questions

1. When should I be worried about my baby’s weight gain?

If your baby is not gaining weight and there are no signs of developmental delays or other issues, the slow weight gain could be your baby’s natural growth pattern. However, if the growth problems persist (i.e., failure to thrive), contact your pediatrician to identify the underlying cause (3) (12).

2. Do breastfed babies gain weight slower?

Yes. According to the CDC, healthy breastfed babies gain weight more slowly than formula-fed babies during their first year of life (13).

3. Which formula milk is best for weight gain?

A study found that babies fed isocaloric cow milk formula (CMF)iXA cow-milk formula formulated to provide similar calories regularly gained weight faster than babies fed extensively hydrolyzed protein infant formula (EHF) or breastmilk (14).

Weight loss in babies is usually not a cause for concern, as they progressively gain weight as they grow. Even though they don’t appear to be overweight, a check may reveal that they are growing properly for their age. If you are worried about your baby not gaining weight or weight gain is happening at an alarmingly slow rate, you should consult your child’s doctor to rule out any underlying causes. Depending on the cause, your pediatrician may recommend treatment, while you can follow some simple guidelines to help your baby gain a healthy weight.

Infographic: Additional Reasons For A Baby Not Gaining Weight

Knowing the other reasons why your baby is not gaining weight could help you understand your baby’s condition and devise a relevant plan with your child’s pediatrician to help your baby gain weight. Let’s look at the infographic below to learn about the reasons your baby is not gaining weight or at a very slow pace.

reasons for a baby not gaining weight (infographic)

Illustration: Momjunction Design Team

Get high-quality PDF version by clicking below.

Download Infographic in PDF version Download Infographic
Download Infographic in PDF version

Key Pointers

  • A baby might not be gaining weight due to poor latching, low milk production, food allergies, or rapid growth and development.
  • If the weight does not increase for a long time, the pediatrician may diagnose to check your baby’s growth pattern.
  • Treating any underlying conditions, avoiding pacifiers until they feed, and increasing the feeding frequency could help the baby gain weight.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
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