Premature infants, known as preemies, come into the world
earlier than full-term infants. Prematurity occurs when a pregnancy
lasts fewer than 37 weeks; full-term infants are born 38 to 42
weeks after the mother's last menstrual period (LMP).
There are many causes of preterm delivery. Sometimes it's
caused by the mother's lifestyle choices during
: smoking, drinking alcohol, using drugs, eating poorly, not
gaining enough weight, exposure to physical stress, and poor
prenatal care are all causes of preterm delivery.
Often, however, the cause is
within the mother's control. The mother could have a hormone
imbalance, a structural abnormality of the uterus, a chronic
illness, an infection, or several other things that could lead to a
premature birth. In addition, preterm delivery is more likely when
a woman is over age 35, under age 19, or is carrying multiple
fetuses. And sometimes the cause is simply unknown.
Premature infants have many special needs that make their care
different from that of full-term infants, which is why they often
begin their lives after delivery in a
neonatal intensive care unit (NICU)
. The NICU is designed to provide an atmosphere that limits stress
to the infant and meets basic needs of warmth, nutrition, and
protection to assure proper growth and development.
Due to many recent advances, more than 90% of premature babies
who weigh 800 grams or more (a little less than 2 pounds) survive.
Those who weigh more than 500 grams (a little more than 1 pound)
have a 40% to 50% chance of survival, although their chances of
complications are greater.
A Preemie's Basic Needs
Premature babies lack the body fat necessary to maintain their
body temperature, even when swaddled with blankets. Therefore,
incubators or radiant warmers are used to keep the babies warm.
Incubators are made of transparent plastic, and they completely
surround an infant to keep him or her warm, decrease the chance of
infection, and limit water loss. Radiant warmers are electrically
warmed beds open to the air. These are used when the medical staff
needs frequent access to the baby for care.
Nutrition and Growth
Premature babies have special nutritional needs because they
grow at a faster rate than full-term babies and their digestive
systems are immature. Neonatologists (pediatricians who specialize
in the care of newborns) measure their weight in grams, not pounds
and ounces. Full-term babies usually weigh more than 2,500 grams
(about 5 pounds, 8 ounces), whereas premature babies weigh anywhere
from about 500 to 2,500 grams.
So, what are premature babies fed? Breast milk is an excellent
source of nutrition, but premature infants are too immature to feed
directly from the breast or bottle until they're 32 to 34 weeks
gestational age. Most premature infants have to be fed slowly
because of the risk of developing
necrotizing enterocolitis (NEC)
, an intestinal infection unique to preemies. Breast milk can be
pumped by the mother and fed to the premature baby through a tube
that goes from the baby's nose or mouth into the stomach.
Breast milk has an advantage over formula because it contains
proteins that help fight infection and promote growth. Special
fortifiers may be added to breast milk (or to formula if
breastfeeding isn't desired), because premature infants have
higher vitamin and mineral needs than full-term infants. Nearly all
premature babies receive additional calcium and phosphorus either
by adding fortifier to breast milk or directly through special
formulas for preemies. The baby's blood chemicals and minerals,
such as blood glucose (sugar), salt, potassium, calcium, phosphate,
and magnesium, are monitored regularly, and the baby's diet is
adjusted to keep these substances within a normal range.
Common Health Problems of Preemies
Premature infants are prone to a number of
, mostly because their internal organs aren't completely ready
to function on their own. In general, the more premature the
infant, the higher the risk of complications.
A common treatable condition of premature babies is
hyperbilirubinemia, which affects 80% of premature infants. Infants
with hyperbilirubinemia have high levels of
, a compound that results from the natural breakdown of blood. This
high level of bilirubin causes them to develop
, a yellow discoloration of the skin and whites of the eyes.
Although mild jaundice is fairly common in full-term babies (about
60%), it's much more common in premature babies. Extremely high
levels of bilirubin can cause brain damage, so premature infants
are monitored for jaundice and treated quickly, before bilirubin
reaches dangerous levels. Jaundiced infants are placed under
special lights that help the body eliminate bilirubin. Rarely,
blood exchange transfusions are used to treat severe jaundice.
is another common health problem among premature babies. During an
apnea spell, a baby stops breathing, the heart rate may decrease,
and the skin may turn pale, purplish, or blue. Apnea is usually
caused by immaturity in the area of the brain that controls the
drive to breathe. Almost all babies born at 30 weeks or less will
experience apnea. Apnea spells become less frequent with age.
In the NICU, all premature babies are monitored for apnea
spells. Treating apnea can be as simple as gently stimulating the
infant to restart breathing. However, when apnea occurs frequently,
the infant may require medication (most commonly caffeine or
theophylline) and/or a special nasal device that blows a steady
stream of air into the airways to keep them open.
Many premature infants lack the number of
red blood cells
necessary to carry adequate oxygen to the body. This complication,
, is easily diagnosed using laboratory tests. These tests can
determine the severity of the anemia and the number of new red
blood cells being produced.
Premature infants may develop anemia for a number of reasons. In
the first few weeks of life, infants don't make many new red
blood cells. Also, an infant's red blood cells have a shorter
life than an adult's. And the frequent blood samples that must
be taken for laboratory testing make it difficult for red blood
cells to replenish. Some premature infants, especially those who
weigh less than 1,000 grams, require red blood cell
Low Blood Pressure
Low blood pressure is a relatively common complication that may
occur shortly after birth. It can be due to infection, blood loss,
fluid loss, or medications given to the mother before delivery. Low
blood pressure is treated by increasing fluid intake or prescribing
medications. Infants who have low blood pressure due to blood loss
may need a blood transfusion.
Respiratory Distress Syndrome
One of the most common and immediate problems facing premature
infants is difficulty breathing. Although there are many causes of
breathing difficulties in premature infants, the most common is
called respiratory distress syndrome (RDS). In RDS, the
infant's immature lungs don't produce enough of an
important substance called
. Surfactant allows the inner surface of the lungs to expand
properly when the infant makes the change from the womb to
breathing air after birth. Fortunately, RDS is treatable and many
infants do quite well. When premature delivery can't be
stopped, most pregnant women can be given medication just before
delivery to hasten the production of surfactant in the infant's
lungs and help prevent RDS. Then, immediately after birth and
several times later, artificial surfactant can be given to the
infant if needed. Although most premature babies who lack
surfactant will require a breathing machine, or ventilator, for a
while, the use of artificial surfactant has greatly decreased the
amount of time that infants spend on the ventilator.
Bronchopulmonary dysplasia (BPD) is a common lung problem among
premature infants, especially those less than 1,000 grams (2.2
pounds) at birth. The exact mechanism for this disease is still
unclear, but extreme prematurity, severe RDS, infections before and
after birth, and the prolonged use of oxygen and/or a ventilator
needed to treat a lung disease all play a major role in the
development of BPD. Preemies are often treated with medication and
oxygen for this condition.
Infection is a big threat to premature infants because
they're less able than full-term infants to fight germs that
can cause serious illness. Infections can come from the mother
before birth, during the process of birth, or after birth.
Practically any body part can become infected. Reducing the risk of
infection is why frequent hand washing is necessary in the NICU.
Bacterial infections can be treated with antibiotics. Other
medications are prescribed to treat viral and fungal
Patent Ductus Arteriosus
is a short blood vessel that connects the main blood vessel
supplying the lungs to the aorta, the main blood vessel that leaves
the heart. Its function in the unborn baby is to allow blood to
bypass the lungs, because oxygen for the blood comes from the
mother and not from breathing air. In full-term babies, the ductus
arteriosus closes shortly after birth, but it frequently stays open
in premature babies. When this happens, excess blood flows into the
lungs and can cause breathing difficulties and sometimes heart
failure. Patent ductus arteriosus (PDA) is often treated with a
medication called indomethacin or ibuprofen, which is successful in
closing the ductus arteriosus in more than 80% of infants requiring
these medications. However, if medical therapy fails, then surgery
may be required to close the ductus.
Retinopathy of Prematurity
The eyes of premature infants are especially vulnerable to
injury after birth. A serious complication is called retinopathy of
prematurity (ROP), which is abnormal growth of the blood vessels in
an infant's eye. About 7% of babies weighing 1,250 grams (2.75
pounds) or less at birth develop ROP, and the resulting damage may
range from mild (the need for glasses) to severe (blindness). The
cause of ROP in premature infants is unknown. Although it was
previously thought that too much oxygen was the primary problem,
further research has shown that oxygen levels (either too low or
too high) play only a contributing factor in the development of
ROP. Premature babies receive eye exams in the NICU to check for
After the NICU
Premature infants often require special care after leaving the
NICU, sometimes in a high-risk newborn clinic or early intervention
program. In addition to the regular well-child visits and
that all infants receive, premature infants receive periodic
hearing and eye examinations.
Careful attention is paid to the development of the
, including the achievement of motor skills like smiling, sitting,
and walking, as well as the positioning and tone of the
Speech and behavioral development are also important areas
during follow-up. Some premature infants may require
as they grow up. Infants who have experienced
complications in the NICU
may need additional care by medical specialists.
Also important is support of the family. Caring for a premature
infant is even more demanding than caring for a full-term infant,
and the high-risk clinics pay special attention to the needs of the
family as a whole.
Samir Alabsi, MD
Date reviewed: October 2007
Originally reviewed by:
Joel D. Stenzel, MD
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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