Bradycardia and apnea in premature infants

In premature infants, apnea and bradycardia often occur together, with low blood oxygen levels. Apnea is a period of brief cessation of breathing. It often triggers bradycardia, which is a slow heartbeat.

First, apnea occurs, where the baby stops breathing. Because the baby is not breathing, blood oxygen levels drop. The heart slows down due to low blood oxygen levels.

Apnea and bradycardia are often referred to as “A and B” or “mantras.” Understandably, this situation can be nerve-racking for parents who are already anxious about a baby born at 37 weeks or less.

This article explains apnea and bradycardia, their respective causes, long-term effects, and available treatment options.

oxygen saturation

Oxygen saturation measures the amount of oxygen-carrying hemoglobin in the blood. The blood of a full-term baby, like that of a child or adult, should be 95% to 100% oxygen saturated.

The blood of premature babies receiving extra oxygen is usually kept between about 88% and 94% saturated, not higher, to prevent retinopathy of prematurity, a serious eye disease.

In hospitals, pulse oximeters are used to measure the amount of oxygen in the blood. When the blood doesn’t have enough oxygen, it’s called desaturation. Desaturation can cause lips or skin to appear bluish and cause babies to lose their tint and become “fluffy”.

Importance of O2 Sats for COPD


Apnea is a period in which breathing stops. In premature infants, an apnea is any pause in breathing that lasts longer than 20 seconds, causing a slow heartbeat or a drop in the baby’s blood oxygen levels.

A premature baby (already connected to a monitor) may need a “reminder” to start breathing if the pause is longer than 20 seconds. In this case, the monitor will trigger an alert. If the alarm didn’t prompt the baby to breathe, the nurse would gently nudge the baby or rub their back until the baby was breathing on its own. This is standard operating procedure in most neonatal intensive care units (NICUs).

Pauses are usually temporary

Like adults with sleep apnea, some premature babies don’t need a “reminder” to start breathing. After a short pause, they will start breathing on their own again.


Bradycardia is usually caused by a baby with apnea. Bradycardia means a slower than normal heart rhythm. In newborns, a heart rate of less than 100 beats per minute in infants less than 1,250 grams (or 2 pounds, 12 ounces) or less than 80 beats per minute in older infants is considered bradycardia.

Neonatal nurses are usually well trained to handle both A and B questions. For example, they recorded how often these events occurred, how long they lasted, and how much stimulation the baby needed to resume breathing.

Premature babies breathe differently

Preterm infants “usually experience bouts of heavy breathing, followed by periods of shallow breathing or pauses.”


Often, premature babies experience apnea and bradycardia for a simple reason: their nervous system hasn’t fully developed yet. Without the full resources of the brain’s respiratory center, the lungs are not “tell” to breathe regularly. Nearly half of infants weighing less than 5.5 pounds are prone to apnea.

Apnea occurs because the process in the brain that tells the baby to breathe fails. As a result, the baby repeatedly stops breathing, which is called central sleep apnea. If a baby’s immature muscular system isn’t strong enough to keep the airway open, the condition is called obstructive sleep apnea.

As and Bs can also be traced to other causes such as infections, anemia and neurological problems. But by far the most likely culprit is so-called “apneas and bradycardia in premature infants.” The severity of the condition decreases as the gestational age of the baby increases. In other words, the longer a baby’s central nervous system develops, the less likely they are to be born with As and B.

frequency instability

As and B can occur once, several times, or multiple times a day.

long term impact

Doctors aren’t sure what the long-term effects of apnea and bradycardia are. They know that bradycardia causes a temporary decrease in blood and oxygen levels in the brain. They also knew that preterm infants with more recorded days of apnea episodes scored lower on tests measuring developmental and neurological outcomes at age 3. However, they could not say with certainty that apnea and bradycardia contributed to the lower scores.

One thing doctors do know is that apnea and bradycardia do not directly cause sudden infant death syndrome (SIDS), although these babies may be at higher risk. Emory University School of Medicine said: “Although apnea and SIDS are separate problems in preterm infants, some infants who require NICU care may have a slightly increased risk of developing SIDS later in life. We cannot predict which infants are at risk; there is no guarantee that infants will be at risk. No SIDS in the future. But the vast majority of babies won’t be at risk and won’t need a monitor.”

Separate apnea from SIDS

Although preterm infants generally have a higher risk of SIDS than term infants, apnea in preterm infants does not lead to a higher incidence of SIDS.


If the infant has only occasional episodes that respond to mild stimuli—rubbing of the back, shaking of the hands—may not require further treatment unless the infant is monitored until the episodes stop. If the baby has a color change — pale or blue — the nurse may give the baby extra oxygen.

If the event is caused by an infection or other problem, then treatment problems often also cause the episode to stop.

Infants with frequent apnea may be placed on continuous positive airway pressure (CPAP) to help them breathe. Medications may also be used to treat apnea (and bradycardia) in premature infants. Caffeine is a relatively new treatment for apnea with few side effects and has been largely successful.

Best location

Babies should sleep on their backs or in a crib.

prevent further spells

Understanding what triggers apnea and bradycardia can help nurses and parents minimize the number of episodes in premature babies. Apnea and bradycardia tend to occur during the transition to deep sleep, so prenatal nurses know it’s important to keep babies in deep sleep for extended periods of time.

As a parent, you may wish to coordinate your NICU visit with feeding and assessment times. If you’re visiting while your baby is sleeping, use Room Sounds. Fluctuations in incubator temperature can also lead to As and Bs. Therefore, try to keep the incubator door closed to keep the temperature inside the incubator stable.

good prognosis

Apnea in premature babies “does not cause brain damage, and a healthy baby who goes a week without apnea may never have AOP again”.

When will it go away?

Good news for parents? Once the “premature baby” is mature and ready to go home (about the time the baby is due), the baby is usually no longer at risk for A and B. However, some babies mature more slowly than others and may still experience occasional events. In this case, a home apnea monitoring system and/or pediatric medication may be required.

Also remember that your baby will eat and drink, gain strength increasingly. When doctors say the vast majority of babies do “grow up” with As and Bs, they mean it.


Many hospitals require that babies be free of apnea or bradycardia for a certain number of days before discharge.


Apnea and bradycardia are called “A and B” because they usually occur at the same time. Apnea is a brief period of time (up to 20 seconds) in which a baby’s breathing stops. This state usually triggers bradycardia, which is a low heart rate. As and Bs afflict parents of premature babies for a simple and immediate reason: the baby’s nervous system hasn’t finished developing yet. Without the full resources of the brain’s respiratory center, the lungs are not “told” to take regular breaths. So they don’t. Most premature babies are past A and B by the time they are ready to go home from the hospital.

VigorTip words

As and B often lead to quick and happy endings for parents of premature babies. These infants also generally did not show lasting effects of the disease. But there’s always a lesson to be learned from a health scare, and doctors might say it’s wise for parents to sign up for cardiopulmonary resuscitation (CPR) classes. Suffice to say, this is a no-brainer for anyone responsible for the life and safety of anyone of any age.