A preterm baby’s lungs
Babies born before week 37 of pregnancy are considered preterm. Preterm babies face a higher risk for one or more complications after delivery.
One of the main concerns is the newborn’s lung. A baby’s lungs are typically considered mature by week 36. However, not all babies develop at the same rate, so there can be exceptions. If it’s known ahead of time that a baby will be coming early, some moms-to-be may need a steroid injection before delivery to speed up lung development.
Immature lungs can be dangerous for your baby. Some of the most common complications include the following.
Respiratory distress syndrome (RDS)
The most common lung problem in a premature baby is respiratory distress syndrome (RDS). This was previously known as hyaline membrane disease (HMD).
A baby develops RDS when the lungs do not produce sufficient amounts of surfactant. This is a substance that keeps the tiny air sacs in the lung open. As a result, a premature baby often has difficulty expanding her lungs, taking in oxygen, and getting rid of carbon dioxide. On a chest X-ray, the lungs of a baby with RDS look like ground glass.
RDS is common in premature babies. That’s because the lungs do not usually begin producing surfactant until about the 30th week of pregnancy. Other factors that increase a baby's risk of developing RDS include:
- Caucasian race
- male sex
- family history
- maternal diabetes
RDS tends to be less severe in babies whose mothers received steroid treatment before delivery.
Treatment for RDS
Fortunately, surfactant is now artificially produced and can be given to babies if doctors suspect they are not yet making surfactant on their own. Most of these babies also need extra oxygen and support from a ventilator.
Pneumonia is an infection of the lungs. It’s usually caused by a bacteria or virus. Some babies get pneumonia while they are still in the womb and must be treated at birth.
Babies may also develop pneumonia several weeks after delivery. This is usually because they were on a ventilator for respiratory problems like respiratory distress syndrome or bronchopulmonary dysplasia.
Treatment for pneumonia
Babies with pneumonia often need to be treated with an increased amount of oxygen or even mechanical ventilation (a breathing machine), in addition to antibiotics.
Apnea of prematurity
Another common respiratory problem of premature babies is called apnea of prematurity. This occurs when the baby stops breathing. It often causes the heart rate and oxygen level in the blood to drop.
Apnea occurs in almost 100 percent of babies who are born before 28 weeks gestation. It’s much less common in older premature babies, especially those born at 34 weeks or later.
Apnea usually does not happen immediately after birth. It occurs more commonly at 1 to 2 days of age and sometimes is not obvious until after a baby has been weaned from a ventilator.
There are two main causes of apnea in premature infants.
- The baby "forgets" to breathe, simply because the nervous system is immature. This is called central apnea.
- The baby tries to breathe, but the airway collapses. Air can’t flow in and out of the lungs. This is called obstructive apnea.
Premature babies frequently have "mixed" apnea, which is a combination of central and obstructive apnea.
A baby who is at risk for apnea needs to be connected to a monitor that records the heart rate, the breathing rate, and the oxygen level in the blood.
If any of these rates fall below normal levels, an alarm sounds, alerting the hospital staff that the baby is having an episode of apnea. The staff then stimulates the baby, usually by gently rubbing the baby's chest or back. The baby begins to breathe again.
Occasionally, a baby requires assistance with a bag and mask to begin breathing again.
Treatment for apnea of prematurity
Central apnea can be treated with a medication called aminophylline, or with caffeine. Both of these drugs stimulate the baby's immature respiratory system and reduce the number of episodes of apnea.
If they don't, or if the episodes are severe enough to require the staff to frequently stimulate the baby's breathing with a bag and mask, the baby may need to be put on a ventilator. This will be the case until the nervous system matures. Babies with purely obstructive apnea often need to be connected to a ventilator through an endotracheal tube to keep the airways open.
Apnea of prematurity usually resolves by the time a baby is 40 to 44 weeks of age. This includes the number of weeks of pregnancy plus the number of weeks since the baby's birth.
Sometimes, it’s resolved as early as 34 to 35 weeks. But occasionally, apnea persists and the baby requires long-term therapy. Parents may need to give their baby aminophylline or caffeine, and use an apnea monitor at home.
In that case, parents are trained to use the monitor and to give CPR to stimulate breathing. Babies are not sent home on a monitor unless they are otherwise stable and are having only rare episodes of apnea in a 24-hour period.
Babies with RDS sometimes develop a complication known as a pneumothorax, or collapsed lung. A pneumothorax can also develop in the absence of RDS.
This condition develops when a small air sac in the lung ruptures. Air escapes from the lung into a space between the lung and the chest wall. If a large amount of air accumulates, the lungs can’t expand adequately.
The pneumothorax can be drained by inserting a small needle into the chest. If the pneumothorax accumulates again after being drained with a needle, a chest tube can be inserted between the ribs.
The chest tube is connected to a suction device. It continuously removes any air that has accumulated until the small hole in the lung heals.
Another complication of RDS is bronchopulmonary dysplasia (BPD). This is a chronic lung disease caused by injury to the lungs. BPD occurs in about 25 to 30 percent of babies who are born before 28 weeks and weigh less than 2.2 pounds. It’s most common in very premature babies born between 24 and 26 weeks.
The underlying cause of BPD is not well-understood. But it usually occurs in babies who are on ventilators and/or receiving oxygen. For this reason, doctors think that these treatments, while necessary, may injure a baby's immature lung tissue.
Unfortunately, BPD, in turn, can cause a baby to require continued oxygen therapy and ventilator support. When a baby is 3 to 4 weeks old, doctors sometimes use diuretic medications and inhaled medication. These can help wean a baby from the ventilator and reduce the need for oxygen.
In the past, doctors frequently used steroid medications to treat BPD. But because the use of steroids has been linked to later developmental problems like cerebral palsy, doctors now use steroids in only the most severe cases.
While BPD tends to improve as babies grow, it's not unusual for babies with BPD to continue to receive diuretic therapy and/or oxygen at home for several months.
What is the outlook?
The outlook for a preterm baby with lung problems will depend on several factors, including:
- the type of lung problem they have
- the severity of symptoms
- their age
With advances in modern medicine, the chances of survival followed by normal development continue to improve.
problems in preterm babies be avoided?
The best way to prevent lung problems in a preterm baby is to avoid a premature delivery. This isn’t always possible, however there are several steps you can take to reduce your risk of delivering prematurely:
- don’t smoke
- don’t use illicit drugs
- don’t drink alcohol
- eat a healthy diet
- talk to your doctor about getting good prenatal care