Infants born before completing 37 weeks in their mothers’ uterus are called  premature babies or preterm babies.  The different organ systems of the baby may not have become well developed and mature enough to function independently yet.

• High blood pressure in the mother, poor nutrition, absence of adequate prenatal care, multiple births, and previous history of premature delivery, are some of the risk factors of premature birth.
• Since the organ systems are not yet fully developed, premature babies usually have difficulties associated with feeding and breathing.
• Premature babies are predisposed to brain hemorrhage and prone to acquiring infections.
• The degree of prematurity is directly proportional to the risk of the baby having functional and developmental problems. The earlier the baby is born, the more severe the problems encountered.
• The problems due to prematurity may eventually resolve as the infant grows and matures. Most will not have any lasting effects of prematurity after the first few months.
• Some of the surviving premature babies may have permanent difficulties resulting from prematurity.

The risk of having premature deliveries can be significantly reduced if proper prenatal care is initiated early.Imminent premature deliveries can be delayed for sometime by administering drugs which stop or slow down the uterine contractions of the mother.

If premature delivery is anticipated, the mother is given corticosteroid injections to accelerate the fetus’s lung development so that it may have less breathing related problems even if born early. Corticosteroid therapy helps in preventing intraventricular hemorrhage in the brain too.

The normal term of a pregnancy is 37 weeks to 40 weeks. Approximately 12 % of babies are born earlier than 37 weeks and are called premature or preterm babies. When they are born just two or three weeks premature, they may not be affected by the adverse effects of prematurity. But those who are born several weeks early can have serious and potentially fatal complications after birth. The earlier the baby is born, the more severe the complications of prematurity. Of all the factors responsible for infant mortality, extreme prematurity is the main factor, accounting for the majority of cases. Extremely premature babies who manage to survive are more likely to have permanent problems including serious developmental delays and learning disabilities. However, with adequate medical care immediately after birth, most premature babies develop normally without long-term problems. Adequate prenatal care, when initiated sufficiently early, may significantly reduce prematurity as well as its adverse effects.

Causes

The exact reason for spontaneous premature birth is not always clear. Some mothers are found to be more prone to having premature babies. Some of the factors that predispose expectant mothers to early labor are:

• Very young mothers (teenagers) and older women are prone to early labor.
• Poor socio-economic status is found to be a factor in increasing the risk of premature labor.
• Lack of prenatal care is found to be a reason for many premature births.
• Women carrying multiple fetuses usually have early delivery.
• Previous history of premature births predisposes an expectant mother to preterm delivery.
• Mothers having heart disease or kidney disease may not be able to carry the pregnancy to full term.
• Mothers with high blood pressure or preeclampsia may not be able to continue with the pregnancy when their condition becomes critical.
• Uterine infections such as chorioamnionitis may necessitate early delivery.

Symptoms

Babies born prematurely typically have low birth weight, mostly below five and a half pounds or 2.5 kilograms. Some may be much smaller, weighing just about 1pound or 500 grams. When pregnancy is confirmed, an ultrasound scan is done to determine the exact age of the developing fetus. It would help the doctors calculate the gestational age of the premature baby at the time of birth. Examining the newborn for characteristic age related developmental features also help to determine its age.

The symptoms of prematurity vary from infant to infant depending on how immature the different organ systems are. In most babies born prematurely, the brain and the lungs are not often fully matured. They may have problems with breathing and temperature regulation of the body. Regulation of blood sugar levels also may be difficult. Premature babies often have underdeveloped excretory and immune systems too.

Complications: The complications arising from immaturity are directly related to how premature the infant is, and also to the reason for prematurity. Certain diseases and abnormal conditions in the mother, such as preeclampsia or high blood pressure and diabetes may be the reason for premature delivery.

Complications due to Underdeveloped Brain:  When the brain and the nervous system remain immature, the infant may have several problems:

• Irregular breathing: Breathing irregularities may be present in premature babies if the brain centers regulating breathing are still very immature. Their breathing may be intermittent, often dotted with pauses which last up to 20 seconds or even longer.
• Difficulty in breathing while eating: The brain centers responsible for controlling and coordinating the various mouth, as well as throat movements, involved in swallowing food are still immature in many preterm babies. They may find it difficult to suck in and swallow the food normally. Simultaneous breathing and feeding needs a lot of coordination of different muscle sets, and premature babies may take longer to achieve it.
• Brain hemorrhage: Severely premature infants, especially those who are born before reaching at least 28 weeks of gestation, are at very high risk of brain hemorrhage. It usually starts in the germinal cortex part of the brain, and may reach the ventricles of the brain, which are chambers filled with fluid. The bleeding may be initiated at the time of labor or during delivery. Bleeding may start when the baby displays symptoms of respiratory distress too. Minor hemorrhages resolve by themselves and do not usually precipitate any lasting damage. However, severe hemorrhages may show symptoms such as lethargy in the infants and seizures. It may lead to coma too. The chances of lasting damage to the brain are also higher.

If the brain hemorrhage has been minor or moderate, it may not affect the normal development of the baby. However, newborns that have had severe hemorrhages are likely to have cerebral palsy, delayed development or learning disabilities as they grow. The postnatal care the newborn receives, as well as continued sensory stimulation provided by parents, through holding the baby, singing or playing music, reading etc, go a long way in improving the outcome. Some premature infants succumb to severe brain hemorrhage.

Complications due to Underdeveloped Digestive Tract and Liver: Infants born with immature liver and digestive system due to prematurity have many complications:

• Regurgitation or spitting-up food: The reflux for sucking, as well as swallowing, is not as strong in premature babies as it is in full-term babies. Their stomach is very small and immature, and the digestion, and the movement of food, is slow, resulting in reflux or spitting up of food frequently.
• Damage to the intestines: Babies born extremely prematurely are prone to a condition called necrotizing enterocolitis in which, portions of the intestines become severely damaged and perforated, necessitating surgical repair.
• Jaundice: When red blood cells normally breakdown, the yellow pigment bilirubin accumulates in the blood. It is the function of the liver to remove this yellow pigment from the blood. But when the liver is immature, it cannot clear up the bilirubin efficiently, resulting in yellowing of the eyes and the skin, a condition referred to as jaundice. Soon after birth, premature babies often develop jaundice. When feedings improve and as bowel movements become more frequent, the bilirubin gets removed through the feces, making it bright yellow in color. If high levels of the pigment remain in the blood for prolonged periods, it may lead to a condition called kemicterus, which is brain damage resulting from bilirubin deposits in the brain.

Underdeveloped Immune System: Prematurely born babies are highly susceptible to infections as their antibody levels are extremely low. The antibodies that help fight infections are formed in the mother’s body as she is exposed to various common infective organisms. These substances are transferred into the fetus through the placenta, towards the end of the normal term. Hence, premature babies are deprived of these disease-fighting substances and are prone to infections, especially sepsis, a serious infection of blood, which often has potentially fatal consequences. Since premature babies need several invasive procedures early in life to connect to life saving support systems such as endotracheal tubes for assisted breathing, catheters connecting to the blood stream and feeding tubes, their chances of acquiring infections are also much higher, compared to full-term babies.

Underdeveloped Kidneys: In the mother’s womb, the excretory functions of the fetus are taken care of, by the placenta. When the baby is born, their kidneys should handle the excretory function. The immature kidneys of the premature babies are not capable of handling this new task. There may be problems with the regulation of fluids and salt in the body. Eventually, as the kidneys become more mature, the excretory function also improves.

Underdeveloped Lungs: The respiratory system of the premature babies is one of the least developed as its maturation usually happens towards the last few weeks of pregnancy. That is the reason for a condition called respiratory distress syndrome, very commonly encountered in infants born too early. This condition is characterized by difficulty in breathing, and a bluish tinge to the skin known as cyanosis. Nostrils’ flaring as the breath is taken in, and a grunting sound accompanying exhalation, are signs of respiratory distress. Low blood oxygen level is responsible for the change in skin color. Immature lungs lack a substance called surfactant which lines the air sacs in the lungs, giving them structural stability. In premature infants, the air sacs collapse each time the air is exhaled.

Difficulty Regulating Blood Sugar Levels: Babies born prematurely usually have feeding difficulties due to which their blood glucose levels may decrease to very low levels. Often, glucose supplementation is given intravenously to prevent severe hypoglycemia. Some babies have symptoms such as weakness and listlessness as the blood glucose levels become low, but most remain asymptomatic. They are at risk of hyperglycemia too, if the intravenous administration of glucose becomes excess. Hence, it is essential to keep monitoring the blood sugar of premature babies to maintain optimum levels.

Difficulty Regulating Body Temperature: Premature babies lose heat rapidly from their body, as the surface area of the skin is more, in relation to their body weight, when compared to normal weight infants born at full-term. While newborns born at term needs to be kept warmly covered to prevent loss of body heat, prematurely born infants need to be kept in an artificially heated environment such as an incubator or a crib warmed by a heater. If the premature infant is not kept warm enough, their heart beat increases in an attempt to enhance circulation and warm up the baby. The increased metabolic activity draws much of the energy expenditure towards it; consequently, the infant fails to gain weight, in spite of nutritional support.

Prognosis

With the advances in neonatal care, the survival rate of babies born prematurely has increased over the last few decades. Premature babies have brighter long term prospects too, if adequate care is provided immediately after birth. Mortality, as well as the risk of developmental problems, has reduced significantly in babies who have completed at least 26 weeks in the mother’s womb. However, in those babies born earlier than 26 weeks of gestational age, the risk of cerebral palsy, blindness, and developmental delays is very high. While most premature babies display normal intelligence, some may have learning disabilities necessitating special schooling.

Prevention

It is always better to prevent prematurity in the babies, whenever possible, by treating the conditions in the mother that may lead to early delivery. An expectant mother should look after her health, and should have adequate amount of nutritious food during pregnancy. Habits detrimental to the well-being of the fetus, such as smoking and alcohol consumption, should be stopped. All kinds of drugs should be avoided during pregnancy unless it is specially prescribed by the doctor and unavoidable due to serious health conditions. Prenatal care should be initiated as early as possible and regular visits to the doctor will help in diagnosing and treating complications such as high blood pressure and diabetes which may necessitate early delivery. Prenatal care is especially important for those who are at higher risk of preterm deliveries.

When labor begins early, the expectant mother is usually given drugs which may delay the delivery as long as possible, by slowing down or stopping uterine contractions. Simultaneously, corticosteroids like betamethasone are administered, which would accelerate lung development in the fetus. This would prevent respiratory distress in the in the infant when it is born prematurely. Risk of intraventricular hemorrhage, which occurs frequently in premature babies, is also significantly reduced with the use of corticosteroids.

Treatment

Prematurity is treated as soon as the baby is born preterm. If the newborn has respiratory distress, respiratory support is provided through a ventilator, till the baby’s lungs become capable of independent function. Hyperbilirubinemia or high levels of bilirubin in blood, is treated by phototherapy. Premature babies whose digestive system is not ready yet, are given intravenous nutritional support initially, till they can be fed through tube inserted into the stomach. Eventually, oral feeding is started as the digestive system matures. The ideal food for the baby is the mother’s milk and it reduces the risk of necrotizing enterocolitis, which often affects the intestines of premature babies. Premature babies usually stay longer in the hospital, often many weeks and even months depending on the extent of prematurity as well as the complications resulting from it.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery

Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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