Newborn jaundice and bilirubin screening

What newborn jaundice is

Newborn jaundice happens when a baby has a high level of bilirubin in the blood. Bilirubin is a yellow substance the body makes when it replaces old red blood cells; the liver helps break it down so it can leave the body in the stool. A high level makes the skin and the whites of the eyes look yellow. (MedlinePlus, 2025)

Before birth, the placenta removes bilirubin from the baby's body. After birth the baby's liver takes over, and it can take some time to do this well. Most newborns have some jaundice, usually noticeable at 2 to 4 days old and gone within 2 weeks. (MedlinePlus, 2025) The NHS says the yellow is most noticeable at around 3 days old. (NHS, 2026)

A very high bilirubin level can damage the brain, a condition called kernicterus. MedlinePlus says this is almost always found before the level gets that high. (MedlinePlus, 2025)

Why every newborn is checked before going home

Care teams watch every baby for signs of jaundice in the hospital, and after the baby goes home, family members usually spot it. Any baby who looks jaundiced should have bilirubin measured right away. (MedlinePlus, 2025) MedlinePlus says many hospitals check bilirubin on all babies at about 24 hours of age, and that careful monitoring in the first 5 days of life can prevent most complications. (MedlinePlus, 2025)

Summaries of the AAP 2022 guideline say it recommends a bilirubin check for all newborns born at 35 weeks or later before they go home, by skin meter or blood test, because looking at the skin alone is not accurate enough. (Cureus study, 2025) (AAP, 2022) The check is done between 24 and 48 hours after birth, or before discharge if that is earlier. (Ital J Pediatr, 2026)

Babies more likely to have significant jaundice

MedlinePlus says babies born early are more likely to have jaundice than full-term babies. Severe jaundice can happen with conditions that break down more red blood cells, such as a blood type mismatch between parent and baby (Rh or ABO incompatibility), bleeding under the scalp after a difficult delivery, or infection. (MedlinePlus, 2025)

NICE lists these factors that make significant jaundice more likely: (NICE CG98, 2023)

• being born before 38 weeks;
• a brother or sister who had newborn jaundice that needed light treatment (phototherapy);
• a parent who plans to breastfeed only;
• jaundice that can be seen in the first 24 hours of life. (NICE CG98, 2023)

Babies with any of these get an extra check for jaundice by a health professional in the first 48 hours. (NICE CG98, 2023)

Skin meter or blood test

MedlinePlus says other blood tests, such as a complete blood count, a Coombs test and a reticulocyte count, will likely be done for a baby with jaundice. (MedlinePlus, 2025)

Reading a result: age in hours and risk factors

Bilirubin is normally higher for the first few days of life. To decide whether a baby's level is too high, the provider considers how fast it has been rising, whether the baby was born early, and the baby's age. (MedlinePlus bilirubin test, 2025) NICE says to read bilirubin against the baby's age in hours, using its threshold table and graphs. (NICE CG98, 2023)

The AAP 2022 guideline does the same with hour-specific charts. Summaries say it separates gestational age from neurotoxicity risk factors, which lower the level at which treatment is advised. (Cureus study, 2025) One summary lists these neurotoxicity risk factors: (Pediatr Rep, 2026)

• gestational age under 38 weeks;
• a low albumin level in the blood (under 3.0 g/dL);
• isoimmune hemolytic disease, where antibodies from the parent break down the baby's red blood cells;
• sepsis;
• clinical instability in the previous 24 hours. (Pediatr Rep, 2026)

The 2022 guideline also removed race as a risk factor. (Cureus study, 2025) MedlinePlus gives bilirubin in mg/dL with micromol per litre alongside, and NICE uses micromol per litre. (MedlinePlus bilirubin test, 2025) (NICE CG98, 2023) Whether a level needs treatment is decided by the baby's care team; this page does not cover treatment.

Follow-up visit after going home

MedlinePlus says all babies should be seen by a provider in the first 5 days of life to check for jaundice, timed by when the baby went home (see the next section). (MedlinePlus, 2025) Under the AAP 2022 guideline, the timing of follow-up is set by the difference between the measured bilirubin and the treatment line for the baby's age in hours, together with gestational age and neurotoxicity risk factors. (Ital J Pediatr, 2026) (Cureus study, 2025)

In the UK, NICE says that for well babies born at 38 weeks or later and more than 24 hours old whose level is just below the treatment line, the bilirubin is measured again within 18 hours if they have a risk factor (a sibling who needed phototherapy, or a parent who plans to breastfeed only) and within 24 hours if not. A level well below the line is not routinely re-measured. (NICE CG98, 2023) Jaundice that lasts more than 14 days in babies born at 37 weeks or later, or more than 21 days in babies born earlier, leads to more checks, including the stool and urine color. (NICE CG98, 2023)

When to contact a doctor

MedlinePlus, in full: (MedlinePlus, 2025)

All babies should be seen by a provider in the first 5 days of life to check for jaundice:

• Infants who spend less than 24 hours in a hospital should be seen by age 72 hours.
• Infants who are sent home between 24 and 48 hours should be seen again by age 96 hours.
• Infants who are sent home between 48 and 72 hours should be seen again by age 120 hours.

Jaundice is an emergency if the baby has a fever, has become listless, or is not feeding well. Jaundice may be dangerous in high-risk newborns.

Jaundice is generally not dangerous in babies who were born full term and who do not have other medical problems. Contact the infant's provider if:

• Jaundice is severe (the skin is bright yellow)
• Jaundice continues to increase after the newborn visit, lasts longer than 2 weeks, or other symptoms develop
• The feet, especially the soles, are yellow

Talk with your baby's provider if you have questions.

The NHS says to get an urgent appointment or advice if a baby over 24 hours old looks jaundiced, if diagnosed jaundice is not getting better or is getting worse, or if the pee is dark yellow or brown or the poo is a pale creamy color. It says to call for emergency help if a baby with jaundice is less than 24 hours old, is sleepier than normal or hard to wake, is not feeding, is floppy or stiff or has jerking movements, has a high or low temperature, has no wet diapers, or has trouble breathing. (NHS, 2026)

Where they differ:

• Who gets measured. Summaries of the AAP 2022 guideline say every newborn born at 35 weeks or later has a bilirubin check before going home. (Cureus study, 2025) (Ital J Pediatr, 2026) NICE says to look for jaundice in every baby but not to measure bilirubin routinely in babies who do not look jaundiced. (NICE CG98, 2023)
• Risk factors. NICE's list (born before 38 weeks, a sibling who needed phototherapy, a parent who plans to breastfeed only, jaundice in the first 24 hours) is about who is more likely to develop significant jaundice. (NICE CG98, 2023) The AAP 2022 neurotoxicity risk factors are about lowering the level at which treatment is advised. (Cureus study, 2025) (Pediatr Rep, 2026)
• Follow-up timing. MedlinePlus gives fixed visit ages based on when the baby went home. (MedlinePlus, 2025) The AAP 2022 guideline sets the timing by how far the level is below the treatment line. (Ital J Pediatr, 2026) NICE sets repeat measurements by how close the level is to the line and by risk factors. (NICE CG98, 2023)
• Units. MedlinePlus gives levels in mg/dL with micromol per litre alongside; NICE uses micromol per litre and notes that results vary between lab methods. (MedlinePlus bilirubin test, 2025) (NICE CG98, 2023)

Your doctor decides what your result means for you.

Questions people ask

Is newborn jaundice normal?

Most newborns have some jaundice, called physiological jaundice. It usually shows when the baby is 2 to 4 days old, and most of the time it does not cause problems and goes away within 2 weeks. A very high bilirubin level can harm the brain, which is why babies are checked. (MedlinePlus, 2025)

Is the skin meter as good as a blood test?

The skin meter (transcutaneous bilirubinometer) estimates bilirubin by touching the skin, with no needle. High readings are confirmed with a blood test. Summaries of the AAP 2022 guideline describe the skin meter as a reliable screening tool and the blood test as the measure used for treatment decisions. (MedlinePlus, 2025) (Cureus study, 2025)

Why does my baby's age in hours matter?

Bilirubin normally rises over the first few days, so the same number can mean different things at 24 hours and at 72 hours. NICE says bilirubin levels are read against the baby's age in hours, and MedlinePlus says the provider also considers how fast the level is rising and whether the baby was born early. (NICE CG98, 2023) (MedlinePlus bilirubin test, 2025)

Does every newborn get a bilirubin test?

It depends on the guideline. Summaries of the AAP 2022 guideline say it recommends a bilirubin check by skin meter or blood test for every newborn born at 35 weeks or later before going home. NICE in the UK says not to measure bilirubin routinely in babies who do not look jaundiced, and to check every baby for signs of jaundice instead. (Cureus study, 2025) (NICE CG98, 2023)

When is the follow-up visit after going home?

MedlinePlus says all babies should be seen in the first 5 days of life to check for jaundice, with timing based on how old the baby was when sent home. Under the AAP 2022 guideline, the timing is set by how far the baby's bilirubin is below the treatment line for their age in hours, their gestational age and their risk factors. (MedlinePlus, 2025) (Ital J Pediatr, 2026)

Is jaundice harder to see on darker skin?

Yes. The NHS says the yellow can be harder to see on black or brown skin, and suggests looking at the whites of the eyes and under the tongue or inside the cheeks. NICE says to check the whites of the eyes and gums and to press lightly on the skin, and not to rely on looking alone to estimate the level. (NHS, 2026) (NICE CG98, 2023)

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