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Why is my baby not gaining weight?

Why is my baby not gaining weight?

Why is my baby not gaining weight? And should I be worried?

If you exclusively breastfeed your baby, usually your baby will gain weight consistently if they latch well and feed often. However, if you’re breastfeeding and your baby is not gaining weight or is gaining weight slowly, they might not be getting enough milk.

Newborn babies should take in about 44-60ml of breast milk every 3 hours. Premature babies need more milk than term babies. Generally, your newborn can lose up to 10% of their body weight during the first 5 days of life. By the time they are 10 days to 2 weeks old, they should regain the weight they lost. After that, they should be gaining about 30g per day.

It is important to understand that every baby is different, and some babies just grow more slowly than others. If you are bringing your baby for regular checkups to the pediatrician and they don’t see an issue, then your baby’s weight is likely not a cause of concern. However, if this is a concern for you, always make sure to check with your pediatrician so they can advise your or provide you with ease of mind.

There are some reasons for a slow weight gain. If your baby is not getting enough milk to gain weight consistently, your pediatrician or a certified lactation consultant can help you find the problem and fix it.

Reasons for poor weight gain

Generally, there are 3 reasons as to why your baby is not gaining weight: not taking in enough calories, not absorbing calories or burning too many calories. This could be a result of intestinal issues, which means that they are unable to absorb calories well. Some kids also use a lot of calories due to certain health issues or being born prematurely.

Poor latch

A good latch allows your child to take in breast milk from your breast without getting tired or frustrated. If there is poor latch, or latching on to just your nipple, they won’t be feed very well or easily.

Infrequent breastfeeding

Breastfeed your newborn at least every 2-4 hours throughout the day and night for the first six to eight weeks. If they want to breastfeed more often, put them back to the breast.

Short nursing sessions

Newborns should breastfeed about 8-10 minutes on each side. As they grow older, they won’t need to breastfeed as long to get the breast milk out. However, during the first few weeks, try to keep your baby awake and actively sucking for as long as you can.

Pain or discomfort

If your baby is not comfortable because of a birth injury or an infection in their mouth, they may not breastfeed well, which causes poor weight gain.

Low or delayed milk supply

Some mothers have their milk come in quite late. Other mothers may experience low milk supply, which causes the child to have less milk when they breastfeed.

Learning curve

Some babies take a little longer than others to learn how to coordinate sucking, breathing and swallowing.

Sleepy baby

Newborns can be sleepy and not want to finish the whole nursing session, meaning that they don’t take in enough calories.

Risk factors

Some babies are more likely to face difficulties while breastfeeding. When a child is at risk for breastfeeding difficulties, the chances of growing and gaining weight at a slower pace are higher. Here are some of the risk factors that may affect your baby’s weight gain.

Being born premature or near term

Babies that are born before 37 weeks may not have the strength or energy to breastfeed for a long enough time to get all the breastmilk they need. They are also more likely to be sleepy and experience medical issues.

Oral challenges

It may be difficult for babies to latch on if their mother has hard, engorged breasts/ large nipples. However, infants with small mouths or physical issues like a tongue-tie or a cleft lip can have latching troubles regardless.


Babies with this medical condition makes them very sleepy and not interested in breastfeeding.


Infants with reflux spit up or vomit after feedings. This causes them to lose milk from feeding and the acid from the reflux can irritate their throat and esophagus, which makes it painful to breastfeed.


Infants with an illness or an infection may not breastfeed well. They may not gain weight, or they might even lose weight.

Neurological issues

Neurological issues can impede their ability to latch and nurse properly.

Failure to thrive

Sometimes, if a child shows continued growth deficiency, they may become undernourished, which may be then diagnosed as failure to thrive. This could lead to developmental issues if left untreated. Children with this medical issue need continued medical supervision to address it. If you think your child may have this issue, do seek medical attention asap.

What to do

If you are concerned about your baby’s poor weight gain, it is important to seek medical help as soon as possible. Your pediatrician might suggest:

Checking your baby’s latch: make sure that your baby is latching on correctly. You can try asking your doctor, a lactation consultant, or a local breastfeeding group for help.

Breastfeeding often: Breastfed babies need to be fed every 2-3 hours and whenever they show signs of hunger. Unlike formula-fed babies, who need to be fed every 3-4 hours instead, breast milk is more easily digested and hence need to eat more often.

Keep your baby awake: Try to keep your baby awake and actively breastfeeding for about 20 minutes per feeding. To keep them awake, you can try tickling their feet, changing your feeding position, changing their diaper or burping them.

Address supply issues: If the problem is your low supply of milk, try to take steps to increase it. You can try breastfeeding more often, pumping between feedings, or try our lactation bakes and nursing tea.

Consider supplementing: if your pediatrician thinks it’s necessary, you may have to supplement your baby with additional feedings of either pumped breast milk or infant formula.

However, if all else fails, and your doctor advises it, you may decide to stop exclusively breastfeeding. You can exclusively pump, switch to formula, or do a combination of the two. Infant formula is a safe and healthy alternative and can ensure that your baby gains weight well. If you need to change your breastfeeding plan, try not to feel too down and remember that you’re doing what you need to do for yourself and your child.