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When a baby is born after a full term of 39-40 weeks, he or she typically weighs two to three kilograms. Soon after birth, the baby loses around 10% of body weight because of fluid loss and some tissue breakdown. But he or she regains this weight quickly, typically within a week-12 days.

As the baby grows, his or her weight and height should gradually increase. Between four to six months after birth, infants gain four to seven ounces per week. They also gain 1.5-2.5 cm in height per month. You might notice that the baby now weighs double their birth weight. In six to 12 months after birth, the baby gains three to five ounces per week and grows around 1 cm a month. Paediatricians say that by the age of one year, your baby should weigh triple the weight they had at birth and should increase in length by 50%.

However, there can be some reasons such as metabolic disorders (childhood diabetes) or premature birth which may lead to slow weight gain in a newborn. According to the American Academy of Pediatrics, if you see that your baby is not gaining weight immediately after birth, you should not panic.

Here in this article, we will tell you about the reasons why your baby could be underweight and some ways to increase your baby’s weight.

  1. How to tell if your baby is underweight?
  2. Possible reasons for underweight babies
  3. Tips for underweight newborn to 6-month old baby
  4. Tips for 7-9 month old underweight baby
  5. Tips for 10-12 month old underweight baby
Doctors for Tips to increase your baby's weight

The visible size of the baby is one of the most obvious signs of slow weight gain. You may recognise the small size of your child when compared to children their age. You may notice the weight, height and the size of your baby’s head. The following symptoms may be seen in an underweight baby:

  • The baby is often extremely drowsy and sleepy.
  • The baby does not interact much with the people around or does not show interest in new things.
  • The baby cries and fusses frequently.
  • The baby misses important physical milestones such as rolling over, babbling, sitting up or walking at the appropriate age. (Keep in mind, some children do these things faster than others. Still, if the baby misses the milestone by several weeks or months, then you should get a check-up done.)

There can be various reasons for slow weight gain in babies. For example, it could be a medical condition or social or financial hardship in the family that affects maternal and child nutrition and other factors that contribute to their health.

There are certain medical reasons that can lead to low weight gain in a baby, such as:

  • Premature birth: A premature baby would not be able to suckle or swallow the milk properly as their muscles are not fully developed.
  • Genetic disorders: A child born with a genetic disorder such as Down syndrome may have difficulty suckling and swallowing milk as well.
  • Metabolic disorders: A child with metabolic disorders such as hypoglycemia (low blood sugar levels) and phenylketonuria (increased levels of phenylalanine in the blood) are unable to convert their food into energy, thus they stay underweight.
  • Allergies: Any unknown food allergy or intolerance may limit the amount of food for your baby, thus they become underweight.
  • Cystic fibrosis: Cystic fibrosis is a chronic disease that damages the lungs and digestive system which prevents the child from absorbing calories.
  • Chronic diarrhoea: Chronic diarrhoea (persistent loose motions) would prevent your child from receiving enough nutrition.
  • Anatomical defect: A child born with a structural defect such as a cleft lip and cleft palate would not be able to swallow anything, thus they are prone to remain underweight.
  • Hyperthyroidism: A child with hyperthyroidism (high levels of thyroid hormone in the body) would burn too many calories, which makes them underweight despite getting proper nutrition.
  • Gastroesophageal reflux: A child may suffer from excessive vomiting and severe acid reflux due to low muscle tone or any other neurological reflux. Though most infants with acid reflux improve with time, sometimes a child suffering from excessive vomiting may have an underlying condition such as pyloric stenosis. Pyloric stenosis is the narrowing of a muscle between the stomach and the intestines (pylorus) which causes severe, projectile vomiting in the first few months of life.

Other causes which can lead to low weight gain in a baby are as follows:

  • Parents who do not know how to prepare formula milk correctly may leave their child undernourished.
  • Children may become underweight if the parents are unaware of the frequency of meals that are required by their baby or if the parents are unable to provide enough food to the baby.

The following tips can help you increase the weight of your newborn baby gradually:

  • Do not worry if your baby loses a few grams of weight just after birth—that’s normal as the baby will regain the birth weight within a week-12 days.
  • Keep feeding your baby eight to 12 times a day or every two to three hours with breast milk or formula milk. 
  • Do consult your doctor before trying out any new formula milk. 
  • Do not introduce solid food to the baby until he or she is at least four months, and preferably after six months of age. Feeding them solid food too soon can cause digestive problems for your child. (Read more: How to wean your baby)
  • When your paediatrician says it is okay to give your baby solid foods, start with a vegetable or fruit puree (example, avocado and breastmilk puree) or an infant cereal mixed with breast milk or formula milk. Do not force-feed your baby. Once you have introduced a new food item to your baby, wait three days to introduce the next one. This will help you to see if there is any allergic reaction such as diarrhoea or rashes due to the food item. (Read more: Best baby foods for a six month old)

The following tips can help increase the weight of your seven- to nine-month-old baby:

  • At this point, your baby should gain around one kilogram of weight every month. Consult your doctor if your baby gains less than this or more than 2.5 kilograms in a month. 
  • Make sure that the feeding bottles and the other baby utensils are properly sterilized, either by boiling them or by using a steam sterilizer. Proper hygiene in all baby utensils would ensure proper nutrition to the baby.
  • You should always start with semi-solid foods which are densely packed with energy and are protein-rich as they will help in pushing up the weight of your baby.
  • Iron-fortified, single-grain infant cereals and pureed meals are good choices for first foods, especially for infants who have been breastfed, as they provide iron, zinc, protein, and other nutrients. You can give your child cereals such as rice, rice flakes, sago (sabudana), sprouted ragi powder and others in the form of porridge or kheer
  • Give them starchy fruits such as banana and vegetables like potato and sweet potatoes (shakarkandi) to increase their weight. You can steam and mash the potatoes and add a little bit of butter in it. You can either mash the banana and mix it with jaggery (gud) powder or you can add breast milk or formula milk (avoid giving your child cow milk till at one year of age as it is known to cause allergy in very young children). You can also give your baby steamed stick of beans and carrot, as it will not only provide the starch content but would also help in soothing the gum of the baby as the baby would be teething at this time.
  • You can give them boiled and well-mashed pulses such as the green gram. You can add a spoon of ghee or butter to it. You can also make a light khichdi with pulses and rice for your baby.
  • You can give curd or yoghurt to the baby along with mashed bananas or jaggery.

Read more: Best baby foods for 7 to 9 months old baby

Following these tips could help you increase the weight of your 10- to 12-month-old baby:

  • At this point, your baby should weigh triple their birth weight. Contact your doctor if the weight gain is slower.
  • By this age, your child will have four or five teeth in their mouth. So besides purees, porridge and kheer, you can add mashed chapatti with lentil soup and scrambled eggs (properly cooked through) to their diet. You can also feed them rice cakes (idlis, appams and steamed pithas are all good choices) along with a spoonful of butter or ghee.
  • You can add fruits in their yoghurt, custards or you can blend their fruit into smoothies such as banana and milk smoothie. You may add other fruits such as mangoes and apples.
  • If your paediatrician agrees, you can give your child scrambled eggs and also well-steamed mashed meat.
  • High fat milk-based puddings like rice kheer with raisins (cooked and mashed), custard and vermicelli can also be given to the baby after 12 months to push up their weight. Full-fat dairy products should be avoided in babies who have a family history of obesity or heart disease.
Dr. Adarsh Bagali

Dr. Adarsh Bagali

Pediatrics
5 Years of Experience

Dr Bishant Kumar

Dr Bishant Kumar

Pediatrics
10 Years of Experience

Dr. Maitreye Datta

Dr. Maitreye Datta

Pediatrics
10 Years of Experience

Dr. Indrajeet L Bahekar

Dr. Indrajeet L Bahekar

Pediatrics
6 Years of Experience

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