Very Low Birth Weight

Very low birth weight (VLBW) is a
term used to describe babies who are born weighing less than 3 pounds, 4 ounces (1.5
kilograms). It is very rare that babies are born this tiny. Only about 1% of babies
in the U.S. are very low birth weight.

The main cause of a baby having
VLBW is being born too early. This is called preterm or premature birth. Premature
a baby is born before 37 weeks of pregnancy. Very-low-birth-weight babies are often
before 30 weeks of pregnancy. A premature baby has less time in the mother’s uterus
grow and gain weight. Much of a baby’s weight is gained during the later part of

Another cause of very low birth
weight is when a baby does not grow well during pregnancy. This is called intrauterine
growth restriction (IUGR). It may happen because of problems with the placenta, the
mother’s health, or birth defects. Most very low birth weight babies who have IUGR
also born early. They are usually very small and physically immature.

A baby is more likely to be very
low birth weight if he or she is premature or has intrauterine growth restriction.
things linked to the mother can increase the risk for VLBW, growth restriction, and
prematurity. They include:

  • Having an infection during
  • Not gaining enough weight during
  • Having a previous pregnancy with a
    low-birth-weight baby
  • Smoking
  • Using alcohol or illegal drugs
  • Being younger than age 17 or older
    than age 35
  • Being African American

Babies with very low birth weight
look much smaller than other babies of normal birth weight. A very-low-birth-weight
baby’s head may look big compared to the rest of his or her body. A baby with VLBW
looks very thin with little body fat. Blood vessels can be easily seen through the

One of the main reasons for regular
prenatal exams is to make sure your unborn baby is growing well. During pregnancy,
size of your baby is estimated in different ways. Your steady weight gain is one way
checking on the baby’s growth.

Another way is to measure the top
of your uterus from the pubic bone (fundal height). The number of centimeters measured
is usually the same or close to the number of weeks of pregnancy. If the fundal height
measurement is low for the number of weeks you are pregnant, it may mean that your
is not growing well.

Other ways to check the baby’s
growth are:

  • Using ultrasound to estimate the
    baby’s growth and development. Your healthcare provider can use measurements of your
    baby’s head, belly, and upper leg bone to estimate his or her weight.
  • Comparing your baby’s estimated birth
    weight with his or her gestational age. The provider may use a formula to figure out
    your baby’s body mass.

A birth weight of less than 5
pounds, 8 ounces (2.5 kilograms) is diagnosed as low birth weight. Babies weighing
than 3 pounds, 4 ounces (1.5 kilograms) at birth are considered very low birth

Treatment will depend on your
child’s symptoms, age, and general health. It will also depend on how severe the
condition is. Babies with VLBW may need:

  • Care in the neonatal intensive care
    unit (NICU)
  • Temperature-controlled beds
  • Special feedings, sometimes with a
    tube into the stomach if the baby can’t suck
  • Other treatments for

The outcome for a baby with VLBW
depends mainly on how much the baby weighs and how many weeks of gestation the baby
is at birth. The smallest and earliest babies have the most problems. They are less
likely to survive.

Babies with VLBW may have a harder
time catching up in physical growth because they often have other problems. Many
very-low-birth-weight babies are referred to special follow-up healthcare programs.

Babies with a very low birth weight
have a greater risk of developing problems. Their tiny bodies are not as strong as
babies of normal weight. They may have a harder time eating, gaining weight, and
fighting infection. They have very little body fat. So they often have trouble staying
warm in normal temperatures.

Most babies with a very low birth
weight are also premature. This can make it hard to separate the problems caused by
prematurity from the problems of just being so tiny. In general, the lower the baby’s
birth weight, the greater the risks for complications. Here are some of the most common
problems of babies with VLBW:

  • Low blood sugar levels at birth
  • Retinopathy of prematurity, an eye disorder that can cause
  • Low oxygen levels at birth
  • Trouble staying warm
  • Trouble feeding and gaining
  • Infection
  • Breathing problems because of immature
    lungs (respiratory distress syndrome)
  • Nervous system problems, such as
    bleeding inside the brain or damage to the brain’s white matter
  • Serious digestive problems, such as
    necrotizing enterocolitis
  • Sudden infant death syndrome

Almost all very-low-birth-weight
babies need special care in the NICU until they can gain weight and are well enough
go home.

Risks for long-term problems and
disability are increased for babies with VLBW. Long-term complications may include:

  • Cerebral palsy
  • Blindness
  • Deafness
  • Developmental delay 

Talk with your baby’s healthcare
provider about your baby’s risks for complications.

There have been advances in the
care of sick and premature babies. More babies today survive even though they are
early and very small. But preventing preterm births is one of the best ways to prevent
very low birth weight.

Regular prenatal care is the best
way to prevent preterm births and very-low-birth-weight babies. At prenatal visits, your
health and the health of your unborn baby are checked. It is important to:

  • Follow a healthy diet during
    This will help you gain enough weight to help your baby grow and
    help you stay healthy. 
  • Not use alcohol, cigarettes, or illegal
    All of these can cause low birth weight and other problems for your
  • Very low birth weight is a term used
    to describe babies who are born weighing less than 3 pounds, 4 ounces (1.5
  • The main cause of very low birth
    weight is being born too early, called premature birth.
  • Treatment for very low birth weight
    babies includes care in the NICU, temperature-controlled beds, and special
  • In general, the lower the baby’s birth
    weight, the greater the risks for complications.
  • Prenatal care is a key factor in
    preventing preterm births and very low birth weight.

Tips to help you get the most from
a visit to your child’s healthcare provider:

  • Know the reason for the visit and what
    you want to happen.
  • Before your visit, write down
    questions you want answered.
  • At the visit, write down the name of a
    new diagnosis, and any new medicines, treatments, or tests. Also write down any new
    instructions your provider gives you for your child.
  • Know why a new medicine or treatment
    is prescribed and how it will help your child. Also know what the side effects
  • Ask if your child’s condition can be
    treated in other ways.
  • Know why a test or procedure is
    recommended and what the results could mean.
  • Know what to expect if your child does
    not take the medicine or have the test or procedure.
  • If your child has a follow-up
    appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your child’s
    provider after office hours. This is important if your child becomes ill and you have
    questions or need advice.