Low Birth Weight: Causes, Symptoms, Managements

Premature birth baby

What Is Low Birth Weight?

Low birth weight (LBW) is refer to birth weight of 2.5 kg or less, than that, whereas the normal birth weight of the baby is 2.5-3.5 kg.

In India for all practical purposes is considered to be 2 kg, and about 18% of babies are born with LBW in India, and 15% around the world.

LBW is allied with preterm birth, intrauterine growth restriction (when a baby in the womb does not grow as expected), or both.

Birth weights are classified as:

  • High birth weight means – greater than 4.2 kg
  • Normal birth weight is between 2.5 to 4.2 kg
  • low birth weight is considered less than 2.5 kg
  • Very low birth weight is considered less than 1.5 kg
  • extremely LBW is less than or equal to 1 kg

Low birth weight is most commonly caused by premature birth (considered less than 37 weeks gestational age) (1)

Babies born prematurely are known as preemies or premies.

The lungs are one of the last organs to mature in the womb this is why premature babies spend the first days or weeks lives in ventilators.

Premature birth baby
Low Birth Weight Is Associated With Premature Birth


In LBW there are two types of babies include:

Preterm babies: It means – born before 37 weeks of gestation (2)

Intrauterine growth restriction (IUGR): This means – babies are born on gestation, but their weight is less than normal also called small for date babies.

Causes of Low Birth Weight

There are several reasons for low birth weight which include:


It is one of the major reasons for LBW in rural areas, or low-economic countries, where lack of proper nutrition, leads to LBW (3)

Malnutrition is also considered one of the major reasons for morbidity and mortality in children under 5 years of age (4)

It is associated with fetal growth retardation. and linear relationship between maternal nutrition and birth weight (5)

Hard physical labor

Several studies found that shifting work, lifting heavy weight, and hard physical work is associated with premature birth (6).

Every year about 15 million babies are born early, which is the most common death among infants worldwide.

Premature Birth

Premature delivery is also associated with low birth weight (less than 2500 grams) or restricted intrauterine development (7)

There are several causes of pre-term delivery which include:

  • The common cause of pre-term birth is the initiation of labor with or without the rupture of the membrane.
  • Diseases or illnesses include:
  • Certain maternal health issues like:
    • a weak cervical opening early
    • IUGR severe intrauterine growth restriction (fetus is smaller than expected during pregnancy) also leads to preterm labor.
    • Stressful life events, such as the death of a loved one or domestic violence
    • Multiple miscarriages or abortions
    • Physical injury or trauma
  • Several other issues are:
    • Previous premature birth
    • smoking, and too much alcohol
    • lack of nutrition before and during pregnancy
    • certain infections such as lower genital tract
    • being overweight and underweight
    • Physical injury or trauma


The very-low-birth-weight infant is at high risk for developing an infection during the antenatal, and postnatal periods (8)

As we know that pre-term delivery that happens at 37 weeks of gestation is allied with low birth weight.

LBW has increased the risk of death, and also remains the increased risk of infection past the 5 years of life.


According to the CDC, women who are exposed to secondhand smoke while pregnant are more chances to have LBW babies.

Smoking makes it harder for women to get pregnant, and in men, it can cause erectile dysfunction.

In fact, The number of smokers worldwide increased to 1.1 billion in 2019 and causing 7.7 million deaths.

Several studies proved that smoking during pregnancy leads to LOW, and can cause tissue damage in the lungs, and brain of the baby.

Air pollution

Pregnant women in developing countries are a high rate of LBW, due to frequent and heavily exposed to indoor air pollution.

Particles (even non-visible) through the air when inhaled harm the fetus and that leads to:

  • Inflammation
  • stress
  • endocrine disruption (a man-made substance that may interfere with the baby’s hormones)
  • impaired oxygen transport access to the placenta heightening the risk of LBW (9)

Other Reasons for LBW

There are several other risk factors that may contribute to low birth weight including:

  • Short maternal height
  • young age
  • unregulated fertility
  • multiple pregnancies
  • previous LBW case
  • high BP
  • celiac disease
  • excessive alcohol, and smoking use
  • insufficient pre-birth care
  • high blood levels can cause miscarriage, premature, and LBW (10)

Studies were shown that pregnant women who exposure to airplane noise are also allied with LBW.

Effect of LBW On Child

Neonates with LBW have a 20 times greater risk of dying than normal birth-weight babies (11) (12).

There are several effects of low birth weight on children which are associated with:

  • Long-term neurologic disability
  • communication disorder (13)
  • difficult in learning than other normal students
  • Increased risk of chronic diseases include heart, lung, and diabetes
  • brain bleed
  • acute respiratory distress syndrome (ARDS) occurs when fluid builds up in the tiny air sacs (alveoli) in your lungs
  • blindness
  • immunity also could be hampered
  • sepsis (an extreme body reaction to infection)
  • digestive disorder

Signs and Symptoms

After the birth of the baby doctor easily confirm that baby has a low birth weight or normal weight.

However, there are some other signs that the mother can also be seen that baby has LBW or normal weight. include:

  • Low-fat tissue
  • inability to maintain body temperature
  • trouble in breathing
  • difficulty in feeding milk, tired so fast
  • small size
  • fine hair covering much of the body
  • yellow skin may be seen which indicates the baby is jaundiced

Check Out – Obesity, And Pregnancy, Is Any Relation B/W Them, Risk

Is Premature Different from LBW?

Yes, is different from LBW, premature birth is considered when the baby is born before the 37th week (8.5 months) of pregnancy.

Whereas, LBW is considered a birth weight of the baby is less than 2.5 kg or 2.5 kg.

Also, Premature delivery is highly also associated with low birth weight or IUGR (a condition when the baby does not grow as expected in the womb)

Low birth weight and premature remains the leading cause of mortality in children under 5 years of age.

Prevention of Low Birth Weight In Mother

Prevention depends on what cause of it, if the infection is the reason, then avoiding the risk of infection can reduce the chance of LBW.

If the environmental factor is the reason then avoiding them may reduce the chance of LBW (14)

To reduce the chances of inhaling polluted air, pregnant women should take care of themselves through these tips are:

  • Reducing outdoor activities
  • always wear a mask, when you go outside
  • avoid high traffic roads
  • use air purifier
  • avoid second-hand smoking

If the mother is malnutrition, then simply increase her food intake with supplementary feeding and proper nutrition.

If LBW is occur due to infection Controlling or treating infections can prevent LBW.

Early detection and treatment of medical disorders like hypertension and diabetes may also reduce the chance of LBW.

If we talk indirect intervention include:

  • Family planning
  • avoid smoking
  • improved sanitation
  • maternity leave with full wages

Management of LBW babies

If the Baby’s weight is very low under 2 kg, then the doctor suggests neonatal care in NICU until the weight reaches 2 kg.

If babies are between 2 to 2.5kg during birth, then this can be followed to take care of LBW babies including:

Proper malnutrition

As LBW babies cannot suck milk properly, they get tired faster, so frequent breastfeeding must be given almost every alternate hour.

For feeding nasal catheter is also done which is a special tube that carries milk, and medicine to the stomach through the baby’s nose.

Prevention of Infection

  • Gently and with minimal handling
  • handling with a clean hand
  • the room should be warm and clean
  • vaccination at the right time
  • the doctor may also prescribe antibiotics medicines

Prevention of cold Temperature

LBW babies are at higher risk of hypothermia due to low body fat and decreased brown fat stores.

There are several ways to the prevention of hypothermia including:

  • Plastic wraps
  • heated pads
  • mother babies skin to skin contact decreases the risk of hypothermia
  • avoid bath to baby till baby reach 2.5 kg weight
  • a doctor can keep the child under an incubator, to maintain the temp, humidity, and oxygen supply.

Mothers can also Provide KMC (Kangaroo Mother Care) where infants placing the skin to skin connect with the mother.

There are some parameters to be monitored during KMC such as:

  • Check baby temperature every 6 hour
  • feeding
  • will educate mothers about their baby’s health, if they see any discomfort in a baby
  • checking

Down Line

Premature birth that happens at 37 completed weeks of gestation is known as premature delivery.

LBW is considered to birth weight of 2.5 kg or less, than that, whereas the normal birth weight of the baby is 2.5-3.5 kg.


Hello, I'm Sahil bisht, I am a Mechanical engineer, As well as, aspiring blogger with an obsession for health. This blog delicate to people who want to learn in health.

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