Top 12 Causes Of Low Birth Weight In Babies

4 min read

Written by Pradeep


Low birth weight is one of the prominent ‘new baby concern’ for most parents. Let us try to understand this phenomenon better.
Newborn baby weighed

What Is Considered As Low Birth Weight In Babies?

A baby whose birth weight is less than 2.5 kilograms is considered to have low birth weight. About 6% of all babies are estimated to be born with a low birth weight. However, it is important to understand that not all low birth weight babies have some underlying medical condition or problem. Sometimes, babies are just born small for no particular reason.

How Does Low Birth Weight Affect My Child?

In many cases, low birth weight will have no impact on your child’s growth and development. This is especially true if the baby was born full-term with no other underlying medical problems. However, when the baby is born premature, or if the baby is born full-term but with some underlying medical problems, then a low birth weight baby has an increased risk of:

  • Infections
  • Polycythemia (blood thickening)
  • Respiratory Distress Syndrome (RDS)
  • Hypoglycemia
  • Problems in immune system
  • Problems in lung function

How severe these problems are depends on how low the birth weight is. It also depends on the cause of the low birth weight and the stage of pregnancy when growth restriction started.
Additionally, while some people correlate low birth weight to lower intelligence and poor health, but there are no strong evidences to prove these.

What Causes Low Birth Weight In Babies?

The cause of the low birth weight in your child is more important than the actual weight itself. This is because the cause determines your baby’s health as he grows up. The following are the top 12 causes for low birth weight in children:

  1. Preterm birth: If your baby is born before completing 37 weeks inside you, then he will most likely be underweight
  2. Multiple pregnancy: If you are having more than one baby, i.e. if you are having twins or triplets or more, then again individual weight of each of your children might be below 2.5 kgs. This because more babies stretch the uterus and compete for limited nutrients, putting extra strain on the mothers’ body, which can further cause certain deficiencies
  3. Intrauterine Growth Restriction (IUGR): These babies are born full-term but still are “small-for-gestational” age. They are most likely healthy, especially if the lower birth weight is due to genetics. There are two kinds of IUGR:
    • Asymmetrical IUGR: This is caused due to malnutrition or high BP in mothers. The baby will have normal sized head, a thin and small baby and an out of proportion liver
    • Symmetrical IUGR: This is caused due to intrauterine infections, abnormalities in chromosomes and mother’s lifestyle (e.g. alcohol abuse). In this condition, the baby develops slowly throughout the pregnancy and is always below the ideal weight range. These babies are more likely to have health problems throughout their lives
  4. High blood pressure in mother: If mother has high BP, then the blood flow to the baby from the placenta is impacted, resulting in low birth weight
  5. Substance abuse by mother: If mother smokes or uses illegal drugs or alcohol, it can restrict the baby’s growth and hence impact his weigh. Harmful chemicals are released in the placenta which results in reduced supply of oxygen to the baby, and thus inhibiting the growth and development
  6. Placenta related problems: If the mother is affected by any of the placenta-related problems (e.g. pre-eclampsia or placenta previa), then the flow of blood and nutrients to the baby is impacted, resulting in lower weight
  7. Diabetes: While diabetes is known for resulting in a big baby, it can also result in preterm birth which will impact baby’s weight
  8. Uterus abnormalities: Sometimes the baby cannot grow big due to the restrictions imposed by the uterus, such as fibroids and uterine malfunctions
  9. Cervix abnormalities: If the mother has cervix abnormalities, it can also result in low birth weight. An incompetent cervix may spur a premature delivery and birth as it gets pressurized to open as the baby grows. Cerclage, a stitch on the cervix is generally put and the mother is advised complete bed rest in many cases
  10. Nutrition of mom: If the mother has not gained enough weight during pregnancy due to malnutrition or imbalanced diet, it can affect baby’s weight. A baby needs a constant supply of nutrients to grow and develop, and mother’s diet is the primary source of nutrition for her. Not eating a balanced and a healthy diet can increase the chances of having a low birth weight baby
  11. Infections during pregnancy: Infections and the drugs used to fight infections can impact baby’s weight gain. Read more on infections during pregnancy here
  12. History: Prior pre term deliveries or low birth deliveries will increase the probability of a low birth delivery subsequently

Factors that affect weight

How Can I Help My Baby Overcome Low Birth Weight?

There are many things that you can do to give your child a healthy start and overcome the problems associated with low birth weight:

  • Breastfeeding: This is an excellent way not just to increase your baby’s weight but to strengthen his immune system as well
  • Checkups: Early detection of problems can help deal with them better. Keep watch for any growth and development delays using any standard baby milestones map
  • Healthy weight gain: It might be tempting to give your child artificial and refined food to help them gain weight quicker. This might not be a good idea. Stick to breast feeding or formula feeding in the initial 6 months. Even after introducing solid foods, ensure you give nutritious and balanced home cooked food rather than store brought cereals that can do more harm than good
  • Be patient: Your baby might be kept in NICU initially to help regulate baby’s body temperature. Be patient and positive during this period

If you are pregnant, and worried about low birth weight, there are quite a few things that you can do during pregnancy to reduce the risk of a low birth weight baby. These include good and early prenatal care, balance and nutritious diet, folic acid supplements and regular health checkups. Read on factors that influence ideal weight of infants.
All the best!


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