A “brady” is hospital shorthand for bradycardia, a temporary drop in a baby’s heart rate. In premature infants, it’s defined as the heart rate falling below 80 beats per minute. Bradys are one of the most common events in the NICU, and while they look alarming, most episodes resolve quickly and become less frequent as the baby matures.
What Happens During a Brady
A healthy premature baby’s heart typically beats between 120 and 160 times per minute. During a brady, that rate drops below 80, triggering the bedside monitor alarm that NICU parents quickly learn to recognize. The episode usually lasts only a few seconds, though some can stretch longer.
You might notice your baby’s skin turn pale or slightly bluish, especially around the lips. Some babies become limp or still during an episode. These color and tone changes happen because the slower heart rate temporarily reduces oxygen delivery to the body. Once the heart rate recovers, color and activity return to normal.
Why Bradys Happen in Preterm Babies
The most common cause is apnea of prematurity, a pause in breathing lasting longer than 15 seconds. A premature baby’s brainstem, the part of the brain that controls automatic breathing, hasn’t fully matured yet. When breathing pauses, oxygen levels drop, and specialized sensors near the carotid arteries in the neck detect that change. Those sensors trigger a reflex that slows the heart rate, especially when the lungs aren’t inflating. So the sequence is typically: breathing pauses, oxygen falls, then the heart rate drops.
These three events, apnea, oxygen desaturation, and bradycardia, often cluster together. NICU staff sometimes refer to them collectively as “A’s and B’s” (apneas and bradys) or “spells.”
Gastroesophageal reflux is often blamed for triggering bradys, and many preterm babies are prescribed reflux medications as a result. However, the connection is weaker than most people assume. In one large study that tracked over 12,000 cardiorespiratory events and 4,000 reflux episodes, fewer than 3% of all bradycardia events were actually preceded by reflux. The bradys that did follow reflux episodes were also shorter in duration than those unrelated to reflux. Other potential triggers include infection, temperature instability, and airway obstruction, though immature breathing control remains the primary driver.
What Nurses Do When the Alarm Sounds
Most bradys resolve on their own or with minimal intervention. The first step is usually gentle touch. Nurses typically start by resting a hand on the baby to provide light pressure, then escalate to rubbing the feet, rubbing the back, or repositioning the baby from their side or stomach into a supine position. If the baby was in a prone or lateral position, simply turning them over is one of the most common responses. These tactile cues remind the baby’s immature nervous system to resume breathing, which in turn brings the heart rate back up.
If gentle stimulation doesn’t work, nurses may briefly increase oxygen flow or use a bag and mask to give the baby a few assisted breaths. Episodes that require this level of intervention are less common but do happen, particularly in very early preterm babies.
Caffeine as a Preventive Treatment
The main medication used to reduce bradys is caffeine, given in a precise medical formulation. It works by stimulating the respiratory center in the brainstem, making it more sensitive to carbon dioxide buildup so the baby is less likely to “forget” to breathe. It also blocks certain chemical signals that can suppress breathing drive. Most premature babies in the NICU are started on caffeine shortly after birth and continue taking it daily until their breathing control matures enough that episodes become infrequent.
When Bradys Stop
Bradys are a developmental problem, not a permanent condition. As a baby’s nervous system matures, the episodes become less frequent and eventually stop altogether. The critical milestone is around 43 weeks postmenstrual age (that’s 43 weeks counted from the first day of the mother’s last period, not from the baby’s actual birth date). For a baby born at 28 weeks, this means bradys typically resolve by roughly 15 weeks after birth. For a baby born at 34 weeks, it may only take a few weeks.
Reaching this milestone is one of the key requirements for going home. Before discharge, a baby generally needs to be free of significant episodes, off caffeine, and demonstrating stable breathing and heart rate on their own. Some babies go home on a cardiorespiratory monitor that tracks heart rate and breathing during sleep. Doctors typically discontinue home monitoring once the baby has gone about three months without any event requiring intervention, or two months without any real event showing up on monitor downloads.
Long-Term Outlook
For most preterm babies, bradys that resolve on their own or with gentle stimulation leave no lasting effects. The relationship between the severity of neonatal bradycardia and later developmental outcomes is still not well defined, partly because researchers haven’t established clear thresholds for what constitutes a “significant” brady in terms of how deep the heart rate drops or how long it lasts. What is clear is that the vast majority of premature babies who experienced typical A’s and B’s in the NICU go on to develop normally once their breathing control catches up. Persistent or unusually severe episodes warrant closer follow-up, which your baby’s care team will guide based on the specific pattern and frequency of events.