Infant Low Birth Weight


When a baby weighs less than 5 pounds and 8 ounces at birth, he is classified as a low birth weight baby. Let us have a look on the causes of low birth weight and how it could be treated.

Last Updated: Oct 22, 2020 11:29 GMT

Infant Low Birth Weight
Infant Low Birth Weight
What is low birth weight?

An average newborn weighs around 8 pounds. When a baby weighs less than 2.5 kilograms (5 pounds, 8 ounces) during birth, he is called a low birth weight baby. Low birth weight is common in multiple birth situations like twins and triplets.  Approximately 7.6% of infants in the United States have low birth weight and it is reported that developing countries have a higher incidence of infants with low birth weight.  Babies born with low birth weight have features like thin structure with minimal body fat and disproportionately large head. A low birth weight baby may be healthy, but there are chances that he may face certain health issues.


A low birth weight baby may fit into the following categories.

·         Low birth weight: When a baby weighs less than 2500grams, or 5 lbs 5 oz.

·         Very Low birth weight: When a baby weighs less than 1500gms, or 3 lb 9 oz.

·         Extremely low birth weight: When a baby weighs less than 1000 grams, or 2 lbs 2 oz.


The following are the causes of low birth weight.

1. Premature birth: Low birth weight is common in premature babies (babies born before 37 weeks of gestation). Babies gain weight during the last few weeks of pregnancy and premature babies may find less time to grow and gain weight in the uterus.

2. Intrauterine Growth Restriction (IUGR): Some babies may not grow well during pregnancy due to poor placental function, mother’s health or birth defects. Babies with IUGR may be born early or full-term; premature babies with IUGR may be very small and physically immature and full-term babies with IUGR may be physically mature but small.

3. Maternal age: If the mother’s age is less than 17 or more than 35, she is more likely to have a baby with low birth weight.

4. Mother’s health: If a mother is exposed to illicit drugs, alcohol and cigarettes during pregnancy, she has higher chances of having a baby with LBW. The other causes include low socioeconomic status, poor prenatal care, poor pregnancy nutrition and pregnancy complications (preeclampsia) and any infections in the mother or baby.

5. Race - African-American babies are twice as likely as Caucasian babies to have low birthweight.


During your regular prenatal visits, your baby’s growth is monitored. Your steady weight gain is one of the signs of assessing your baby’s growth. Other methods include

1. Fundal height: To evaluate fundal height, you doctor measures from the top of your pubic bone to the top of your uterus (fundus). Fundal height is expressed in centimeters. If you are 20 weeks pregnant, your fundal height should be 20cms. If the fundus height is less, it may be a sign that your baby is not growing well.

2. Ultrasound: Ultrasound is a more accurate way of measuring your baby’s weight and evaluating the growth pattern.

3. After birth, your baby’ weight is immediately checked and compared with the gestational age. Accordingly your baby is classified as low birth weight or very low birth weight.


Treatment for low birth weight depends on the specific condition. Some low birth weight babies need to stay in hospital until they reach the adequate weight. If your baby’s birth weight is extremely low and have some complications, she will be placed in neonatal intensive care units.  In intensive care units, special temperature controlled beds and feeding techniques will be used.  If a baby cannot suck, special feedings may be required.

The World Health Organization (WHO) suggests frequent breastfeeding to promote the growth of weight gain in LBW infants. Low birth weight babies who have no complications may be able to catch up physical growth and may require follow up health programs.


As their bodies are not physically strong, LBW babies may find difficulties in eating, gaining weight and fighting infections.  Some of the complications a LBW baby experience include

·         Low oxygen levels at birth

·         Trouble staying warm

·         Problems with blood sugar

·         Breathing problems

·         Nervous system problems

·         Digestive problems

·         Sudden infant death syndrome (SIDS)

Some very low birth weight babies may have long term complications like cerebral palsy, blindness and developmental delays.



It is extremely important to get proper prenatal care and follow a healthy diet during pregnancy. Advances in medical care have dramatically increased the survival rates of low birth weight babies. 


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