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Low Birth Weight Infants - Causes, Complications and Management

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6 min read


After birth, the measurement of weight is the first parameter with which not only the immediate health but also the future health of the baby is determined. Read the article to know more.

Medically reviewed by

Dr. Rakesh Radheshyam Gupta

Published At June 29, 2022
Reviewed AtMarch 27, 2023


The birth weight of a newborn is recorded within the first hour of the birth before postnatal weight loss, which ideally should be at least eight pounds. At full term, babies are usually born without any fatal complications. However, preterm babies are born with many health-related complications, congenital defects, neurological defects, and developmental defects like low birth weight.

As per the World Health Organization (WHO), a low birth weight baby is less than 2500 grams weight. The lower the weight, the higher the chances for babies to have complications like unstable vitals and low immunity. Moreover, even if the condition is treated at an early age, there are chances for adulthood complications like chronic diseases and poor cognitive health. Especially developmental difficulties and compromised motor skills are mainly seen in children with low weight. When an infant is born with low birth weight, there are many factors that play a part in it, for instance, genetics, the health of a mother, or multiple births. Some of the low birth weight babies live a healthy life if treated promptly, but some suffer from lifelong fatal diseases and disabilities, and developmental abnormalities.

Additionally, they carry more risk of secondary infections, respiratory distress, vision or hearing impairment, immature development of organs, and disorders related to the gastric system. Furthermore, delayed clamping of the umbilical cord and balanced nutrition in mothers can improve the chances of low birth weight babies.

What Are the Causes Behind Low Birth Weight?

There are many environmental and genetic factors that affect the weight of a newborn, such as:

  • Race - It is proven that black women are more likely to give birth to a child who has a low birth weight.

  • Multiple Births - Twin babies are more likely to have this condition associated with premature delivery.

  • Intrauterine Growth Restriction - The growth of the fetus depends upon genes and the health of a mother. There are many etiological factors affecting the growth of a fetus, such as placental insufficiency, abnormal placenta, chronic diseases, infections during pregnancy, genetic disorders, and multiple pregnancies. Any of these can lead to weight-related problems in neonates.

  • The Health of a Mother - If a mother is suffering from any disease during pregnancy or facing an issue related to lack of nutrition, there are chances that the fetus may suffer from malnutrition.

  • Preterm Birth - If a baby is born before the 37th week of pregnancy, it is considered to be preterm, and this plays a major role in the development.

  • Genetics - Genetic structure plays an essential role in the postnatal growth of the baby. For instance, if either of the parents was suffering from any congenital defects, there are chances of a newborn having the same defect.

  • Substance Abuse - Smoking, alcohol consumption or other drugs related to addiction in the mother during or before pregnancy can hamper the growth of the baby in the womb, which leads to a low birth weight baby.

  • Infection or Medical Condition During Pregnancy - Having heart-related issues like high blood pressure or infectious diseases like rubella or syphilis may cause low birth weight.

  • Medication - During pregnancy, it is mandatory to let the doctor know about all the herbal or over-the-counter medications mother is taking, as it directly affects the growth of the fetus and causes birth defects.

  • Domestic Violence or Abuse - Due to physical or emotional abuse, the stress and violence can cause preterm labor in women; hence the weight of the newborn is affected by this.

  • Age - Mother at the age of 15 or younger or 35 or older brings complications and birth defects.

What Are the Complications Associated With Low Birth Weight?

Birth defects related to the growth of the newborn causes many impacts on the mother and a child, for instance:

  • Organs - Growth of the internal organs completely depends on the overall growth of the baby, and premature birth can cause complications related to organs like lungs, brain, heart, intestine, and more.

  • Temperature Control of the Body - Due to low fat, it is very difficult for babies to stay warm on their own, and as a result, they are kept in an incubator for a particular time.

  • Feeding-Related Issue - Premature babies are so small that it is difficult for them to breastfeed, but due to growth-related issues, they must take a certain amount of calories.

  • Blood Sugar - It is often seen that low birth weight babies face issues like low blood sugar, and for that, they are required to use sugar faster to maintain blood sugar.

  • Low Oxygen Level at Birth - Generally, in preterm births, there are chances of a baby being born with immature lungs that cause airway obstruction, hence the low oxygen in the bloodstream.

  • Infections - Usually, low-weight babies have a compromised immune system, owing to which they are more susceptible to any kind of infections.

  • Breathing Problems - Many babies are seen with infant respiratory distress syndrome related to a birth defect where it is difficult for them to maintain the breathing process normal.

  • Neurological Complications - Commonly, this is seen in premature babies. Complications like intraventricular hemorrhage occur due to respiratory distress and lack of oxygen to the brain.

  • Gastrointestinal Problems - Diseases like celiac disease and inflammatory bowel disease are commonly associated with low birth weight.

  • Sudden Infant Death Syndrome (SIDS) - The etiology of SIDS is still unknown, but it is seen that premature babies are more vulnerable to this due to immunocompromised health.

  • Blindness - Due to lack of oxygen and nutrition in the bloodstream, low birth weight infants are more at risk of losing eyesight.

  • Deafness - Due to premature birth, the physical development of the baby might be interrupted, causing loss of hearing ability.

  • Developmental Delay - Due to preterm labor, the development of the internal organ system was hampered. Owing to this, there are psychological and physical disabilities seen at a later age.

  • Cerebral Palsy - Due to lack of oxygen at preterm birth, there are chances that the development of the brain is compromised, leading to many serious complications like cerebral palsy.

How to Diagnose Low Birth Weight?

  • If a mother is going through regular postnatal and prenatal examinations, it is comparatively easy for doctors to diagnose a baby with growth-related issues.

  • There are many measures to check the growth of the baby in the womb, and one of the ways to check it is checking the fundal height. The height from the pubic bone to the top of the uterus is measured in centimeters. It should be the same as the gestation period; for example, if the pregnancy is 25 weeks, the fundal height should be 25 centimeters. Any irregularity in fundal height shows growth-related complications.

  • Another more accurate mode of measurement is ultrasound, where with the help of sound waves, the intrauterine image of the fetus can be seen. The measurement of the fetus from head to toe is taken to check the growth.

How to Manage Low Birth Weight?

As technology and medicine are advancing, there is an increase in survival rates of babies with growth-related issues. However, prenatal care is much more important to prevent such complications in newborns. Also, while the baby is in NICU and given the best care possible by doctors, their chances of survival are high. If the baby develops any other health-related complications, some professionals measure and provide adequate treatment.

Also, the health of the mother is as important as the health of the fetus. So, mothers should follow the doctor's advice if they are prescribed any supplements or bed rest during pregnancy. Mothers should also avoid using any harmful substances while pregnant and follow a healthy lifestyle with a proper diet.

Some Important Things About Birth Weight:

  1. The weight of a baby at birth should be above 2.5 kg. This weight is known as AGA (appropriate for gestational age).
  2. Low birth weight with normal gestation has low complications as compared to low birth weight with prematurity. So prematurity plays a vital role in future complications and health-related issues.
  3. IUGR (intrauterine growth restriction) babies have more risk of hypoglycemia, hypothermia, sepsis, etc. Prematurity with low birth weight has more likelihood of respiratory distress, congenital diseases, vision and hearing problems, etc.
  4. Race as a cause of low birth weight is not associated much. Instead, poor maternal nutrition, maternal infections, etc., are more associated.
  5. Blindness is seen in premature babies and babies on ventilation who are prone to develop retinopathy of prematurity.
  6. Diagnosis of low birth weight before birth is more accurate with serial USG (ultrasound) examination. Nowadays, anomaly scans are done to see for any congenital malformations, and proper counseling of the parents can be done. USG is also safe for mother and baby as no radiation occurs.
  7. Low birth weight babies, if detected antenatally, can be managed by proper care of the mother and by giving supplements to the mother. Also, postnatally babies are given formula feeds and other medication, which helps in proper growth. Meanwhile, breastfeeding is promoted at all levels for mothers.
  8. The good health of a mother is very important. So it is recommended to do a proper check-up at the antenatal clinic. Family support and help from doctors or midwives help in stress-free pregnancy. Also, the mother should be aware of her diet and should not consume tobacco-related products or other harmful products which might cause problems for her baby.


As soon as the baby starts embryonic development, it is more important for a mother to take care of herself and her baby. In order to prevent the newborn from any birth-related defects and complications, it is essential to provide nutrition and regular checkups during and after pregnancy. However, with advancements in medicine, the morbidity and mortality ratio has comparatively decreased.

Frequently Asked Questions


What Are the Different Types of Low Birth Weight?

The different categories of low birth weight babies are as follows:
- VLBW (very low birth weight) - Newborns with a weight less than 1500 grams.
- ELBW (extremely low birth weight) - If the weight is less than 1000 grams.
- LBW (low birth weight) - Newborns with a weight of 2500 grams or less.


Is Low Birth Weight Associated With Disorders?

Several studies show that newborns with low birth weight may be more associated with disorders than babies with a healthy weight. The associated conditions are:
- Jaundice.
- Infections.
- Patent ductus arteriosus.
- Breathing disorders.
- Diabetes.
- Heart disease, etc.


What Consequences Do Low Birth Weight Babies Have?

Low-birthweight babies may face more consequences than normal-weight babies. It includes:
- Inability to fight infections.
- Difficulty in gaining weight.
- Feeding and eating difficulties.
- Respiratory issues.


What Are the Newborn’s Nursing Diagnoses?

The types of nursing diagnoses are as follows:
- Ineffective breastfeeding.
- Hyperthermia.
- Risk for infection.
- Breathing pattern.
- Delayed development.


What Are the Complications Associated With a Low Birth Weight Baby?

Low-birth babies may have the following complications:
- Immature lungs may cause breathing problems.
- Necrotizing enterocolitis.
- Nervous system disorders.
- Infection.
- Difficulty in gaining weight.
- Sudden infant death syndrome.


How Is a Low Birth Weight Infant Managed?

The low birth weight newborns require the following care:
- Feedings through a tube inserted into the newborn’s stomach.
- The newborn is placed in the neonatal intensive care unit (NICU).
- Temperature-controlled beds.
The babies are followed up after discharge from the intensive care unit.


What Is Considered Extremely Low Birth Weight?

Low birth weight is diagnosed when the newborn weighs less than 2500 grams. However, the extremely low birth weight is confirmed when the baby is even less than 1000 grams. These babies may have more severe complications than the low-birth-weight babies; these include:
- Difficulty in surviving.
- Digestive problems.
- Blindness, etc.


Is Low Birth Weight Considered a Birth Defect?

Low-birth weight is associated with many birth defects. In addition, low-birth-weight babies are mostly born prematurely, that is, before 37 weeks of gestation.
Low birth weight is, as such, not considered a birth defect but the prevalence of birth defects is high in low birth weight babies. Therefore, taking necessary steps to prevent low birth weight babies is essential.


What Is the Survival Rate of Low Birth Weight Babies?

The survival rate decreases in newborns with very low and extremely low birth weight. However, low birth weight newborns may live longer with or without systemic problems. Studies show that the survival rate as:
- Birth weight less than 1000 grams- 32 % survival rate.
- Birth weight of 1000 to 1400 grams - 84 % survival rate.


What Is the Required Newborn Weight to Leave the NICU?

The doctor may monitor a few factors in the newborns allowing them to leave the NICU (newborn intensive care unit). It includes:
- Normal body temperature.
- Absence of events like bradycardia or apnea.
- No breathing difficulties.
- Ability to feed.
- Free of infections.


Can IUGR Babies Be Normal?

The intrauterine growth retardation babies are those who remain small for their gestational age. The risk of health problems is high in these babies compared to other babies. It includes:
- Distress during birth.
- High-risk for infections after birth.
- The long-term consequences have diabetes and cardiovascular disorder.
Dr. Rakesh Radheshyam Gupta
Dr. Rakesh Radheshyam Gupta

Child Health


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