Why Do Newborns Get Jaundice, and When Does It Need Treatment?

Newborn jaundice is a yellow tint to a baby's skin and eyes that happens when bilirubin, a pigment made as red blood cells break down, builds up faster than the baby's immature liver can clear it. It is common and often mild, and many cases fade without treatment. It needs prompt evaluation when the yellow color deepens or spreads, the baby is hard to wake or feeds poorly, or it appears very early. This article covers why it happens and when treatment is considered.

Why newborn jaundice happens

Jaundice is the yellow color that appears when bilirubin collects in the skin. MedlinePlus describes jaundice as a sign that bilirubin is building up in the blood, and it is a common newborn problem. In most healthy babies, several factors contribute at once.

• Extra red blood cells. Babies are born with a high number of red blood cells, and breaking them down produces bilirubin.
• An immature liver. The newborn liver is still learning to process bilirubin and pass it out of the body.
• Slow movement through the gut. Bilirubin leaves mainly in stool. When a baby is feeding little, less bilirubin may be cleared, and some can be reabsorbed.

The exact mix varies from baby to baby, and the mechanism is not fully understood in every case. Mild jaundice that appears after the first day or so and fades over the following weeks is often called physiologic jaundice.

What newborn jaundice looks like

Yellow color usually shows first on the face and may then seem to move down the chest, belly and legs. The whites of the eyes may look yellow. Pressing gently on the skin in good light can make the tint easier to see, though skin tone can make jaundice harder to notice. In babies with darker skin, check the whites of the eyes, the gums and the inside of the lips, and the soles of the feet and palms.

Color alone cannot tell you how high the bilirubin level is. Clinicians combine history, examination and testing, usually a skin-scanning device or a blood test, to decide what the level means for your baby.

Newborn jaundice risk factors

Some babies have a higher chance of bilirubin rising to a level that needs care. Factors that are associated with higher risk include:

• Early birth. Babies born before full term have less mature livers and may feed less well.
• Blood type differences. When a mother and baby have different blood types, including Rh incompatibility, the mother's antibodies may cause extra breakdown of the baby's red blood cells. MedlinePlus has a page on Rh incompatibility.
• Inherited red blood cell conditions. G6PD deficiency and sickle cell disease can raise the amount of red blood cell breakdown.
• Jaundice in a sibling. A brother or sister who needed treatment may point to a shared risk.
• Bruising or a large collection of blood under the scalp from delivery. Blood that is reabsorbed adds to the bilirubin load.
• Trouble feeding. Slow weight gain or too few wet and dirty diapers can contribute.

Yellow color that is visible in the first 24 hours of life needs urgent in-person evaluation with a bilirubin measurement, because it can point to red blood cell breakdown or infection rather than ordinary newborn adjustment. Call your baby's clinician right away; if your baby cannot be seen promptly, go to the emergency room.

Breastfeeding and jaundice

Breastfeeding jaundice and breast milk jaundice are different ideas that people often mix up. The first is associated with a baby who is not yet getting much milk, so less bilirubin leaves in stool. The second describes jaundice that can last longer in otherwise healthy breastfed babies, and its cause is not fully understood. Neither is a reason to stop breastfeeding on your own. If you are worried about how feeding is going, tell your baby's clinician or a lactation consultant so they can check latch, weight and diapers and decide what support or extra feeding makes sense.

How doctors check bilirubin and decide on treatment

Clinicians look at the bilirubin level together with the baby's age in hours, gestational age and neurotoxicity risk factors such as infection, low albumin or an unstable condition, which can lower the level at which treatment starts. The same number can call for different actions in different babies. For that reason, there is no single level that applies to every newborn, and you should not try to judge a result by yourself. US pediatric teams follow the national pediatric clinical practice guideline (2022 revision) for management of hyperbilirubinemia in newborns of 35 or more weeks' gestation and apply it to your baby.

Tests that may be used include:

• A skin-scanning device that estimates bilirubin through the skin.
• A blood test, which measures bilirubin directly and is used to confirm an estimate or when the level looks high.
• Blood type and other blood tests if the clinician suspects red blood cell breakdown.

The national pediatric guideline recommends follow-up after discharge, with timing based on the baby's age at discharge and bilirubin risk, so keep every visit your clinician schedules.

Treatment options

Phototherapy

Phototherapy is the main treatment for newborn jaundice. The baby lies under special blue-spectrum light with the eyes covered, and the light changes bilirubin in the skin into forms that can be passed out in urine and stool. Some studies have compared continuous with intermittent phototherapy, and clinicians choose the approach based on the baby's level and condition. Babies are usually kept feeding during treatment, and your care team will explain how often to feed and how to hold your baby.

Feeding support

Frequent feeding supports diaper output and may help the body clear bilirubin. Clinicians may suggest more feeds, help with latch, or supplementation when it is medically needed.

Hospital treatments for severe cases

When bilirubin is very high or rising fast, or when a blood type conflict is the cause, a baby may need intensive treatment in a neonatal unit. This can include intensive phototherapy, fluids given through a vein, and, in uncommon cases, an exchange transfusion in which a baby's blood is replaced in small amounts. These steps are done by specialists and are not something to manage at home.

Why very high bilirubin matters

For most babies, jaundice is temporary and harmless. According to the national pediatric guideline, very high bilirubin can sometimes affect the brain, a condition called acute bilirubin encephalopathy. This is much less common than ordinary jaundice, and one yellow baby does not mean this will happen. Still, it is the reason clinicians take levels seriously. Signs that bilirubin may be affecting a baby include unusual sleepiness, poor feeding, a high-pitched cry, and arching of the back or neck. These signs need emergency evaluation, as listed in the box below. The same guideline notes that very high untreated bilirubin can rarely cause lasting brain injury called kernicterus, with effects that can include movement problems, hearing loss and gaze problems, which is why timely treatment is part of newborn care.

Jaundice can also occur alongside an infection. In a baby younger than 3 months, a rectal temperature of 100.4°F (38°C) or higher needs emergency evaluation whether or not the baby looks yellow and even if the baby looks well. A low or unstable temperature, or a baby who feels unusually cold, also needs urgent evaluation. Do not give fever medicine to a baby this young unless a clinician tells you to, because it can hide a fever that needs assessment.

Jaundice that lasts or looks different

Jaundice that lingers beyond the first couple of weeks, or that comes with pale or clay-colored stools and dark urine, is evaluated differently. These features can point to a problem with the liver or bile flow, or to an infection such as hepatitis. Liver and bile duct conditions in infants are much less common than ordinary newborn jaundice, and one symptom does not establish them. They are reasons to see a clinician promptly rather than wait.

What you can do at home

• Feed your baby often, and keep a simple log of feeds, wet diapers and stools.
• Keep every follow-up visit your baby's clinician recommends after discharge.
• Look at your baby's skin and eyes in daylight each day.
• Get your baby seen in person the same day if the yellow color is deepening, spreading toward the belly, legs or feet, or if feeding drops off.

Sunlight is sometimes suggested online as a home treatment. Ask your baby's clinician before trying it, since it is not a reliable way to treat significant jaundice and can risk sunburn and overheating.

When to Seek Medical Care