Newborn Care

Newborn Jaundice: What's Normal and When to Worry

By Dr Soubhagya Khare11 September 20267 min read

Seeing your newborn's skin turn yellow can be alarming, but some jaundice is extremely common — an estimated 80% or more of babies develop it. Most of the time it's harmless and needs only watching. This article expands on the jaundice section of our Newborn Care guide, explaining why jaundice happens, how doctors actually decide whether it needs treatment, and the specific signs that mean it needs prompt attention.

Why jaundice happens

Jaundice is caused by a build-up of bilirubin, a yellow substance produced when the body breaks down old red blood cells. Before birth, the mother's body clears this for the baby; after birth, a newborn's own liver has to take over, and it takes a few days to work efficiently. This temporary gap is why jaundice is so common in the first days of life.

Physiological jaundice versus jaundice that needs evaluation

"Physiological" jaundice — the common, expected kind — generally appears after the first 24 hours of life, tends to peak within the first week, and settles gradually as the baby's liver matures and feeding improves.

Jaundice is treated differently, and needs prompt medical evaluation, when it:

Appears within the first 24 hours of life — this is never considered simply "physiological" and always needs assessment
Rises quickly or reaches a high level
Doesn't improve, or is still present, well beyond the first couple of weeks
Occurs in a baby who is preterm, of low birth weight, or unwell for another reason
Is accompanied by poor feeding or excessive sleepiness

A high-pitched cry in a jaundiced baby is a more serious sign specifically — see the urgent warning signs below.

Why there's no single number that applies to every baby

You may hear about "bilirubin levels," but there isn't one threshold that applies the same way to every newborn. Current pediatric guidance assesses bilirubin against your baby's exact age in hours, their gestational age (how early or on-time they were born), and specific risk factors (such as blood group incompatibility with the mother, bruising from birth, or feeding difficulty) — all considered together on a chart designed for this purpose. A bilirubin level that's unremarkable for a 4-day-old term baby could be a genuine concern for a 30-hour-old preterm baby. This is exactly why your doctor's own assessment matters more than any single number you might read about, and why this article won't quote specific thresholds.

Feeding and jaundice

Frequent, effective feeding is one of the most useful things you can do — breastfeeding at least 8–10 times a day (or more, on demand) helps your baby pass more stool, which is how bilirubin actually leaves the body. Two feeding-related patterns are sometimes discussed:

Jaundice related to not-yet-established feeding (sometimes called "breastfeeding jaundice") in the first few days, when a baby isn't yet feeding often or effectively enough — usually improves once feeding is supported and increases.
A later, more gradual jaundice pattern sometimes seen from about the second week onward in some breastfed babies, thought to relate to breast milk composition rather than poor feeding — usually mild and resolves on its own, and stopping breastfeeding is rarely necessary; your pediatrician will guide you individually.

In both situations, the answer is almost always to support and increase breastfeeding, not to reduce it, and never to substitute water, sugar water, or other feeds in its place.

How jaundice is assessed

Your baby will typically be checked for jaundice regularly in the hospital before discharge, and again at follow-up. Assessment usually involves:

A visual check, sometimes supported by pressing gently on the skin
Transcutaneous bilirubinometry (TcB) — a handheld device placed on the skin that estimates bilirubin without a blood draw
A blood test for serum bilirubin when a more precise or reliable number is needed, or when TcB isn't accurate enough for the situation (for example, in a preterm baby or a baby jaundiced on day one)

When phototherapy is used

Phototherapy — special blue light that helps the body break down and clear bilirubin — is the standard, well-established treatment when bilirubin reaches a level your doctor determines needs it, based on the age/gestational-age/risk assessment above. It's generally very safe: your baby is undressed under the light with eyes protected, and feeding continues with brief breaks (breastfeeding doesn't need to stop). How long treatment is needed depends on how quickly your baby's bilirubin responds and their individual clinical circumstances — your doctor will monitor this and let you know rather than working to a fixed timeline. It does not have any lasting effect on your baby's skin tone.

Sunlight is not a treatment

You may hear suggestions to place a jaundiced baby in sunlight. Sunlight is not an established or reliable treatment for newborn jaundice and should never be used as a substitute for proper medical assessment and, if needed, phototherapy — a baby with jaundice serious enough to need treatment needs that treatment, not sun exposure, and unsupervised sun exposure carries its own risks (like sunburn and overheating) for a newborn.

Warning signs needing urgent evaluation

Seek prompt medical assessment if you notice:

Jaundice appearing in the first 24 hours of life
Jaundice that is rapidly worsening or spreading further down the body (arms, legs, palms, or soles)
Jaundice still present or not clearly improving by 2–3 weeks of age
Poor feeding or unusual sleepiness alongside jaundice
A high-pitched cry in a jaundiced baby — this is a more serious sign that can indicate the bilirubin is affecting the nervous system, and needs urgent same-time assessment, not a routine appointment
Pale, white, chalky, or clay-coloured stools, together with dark urine — this combination is abnormal at any time, not only if jaundice has lasted a particular number of weeks, and needs prompt medical assessment whenever you notice it. It can point to a blocked or underdeveloped bile duct (a condition called biliary atresia). This is uncommon, but it's genuinely time-sensitive: outcomes are meaningfully better when it's identified and treated within the first couple of months of life, so don't wait to see if it resolves on its own.

Follow-up after discharge

Most newborns have their first pediatric check within 3–5 days of birth, partly to reassess feeding, weight, and jaundice — sooner if your baby went home early or has any risk factors. Keep this appointment even if your baby seems well, and don't hesitate to seek an earlier review if you're concerned in between visits. See our Newborn and Infant Care service page for more on what these check-ups involve, and Signs Your Newborn Needs Urgent Medical Attention for a broader safety checklist beyond jaundice.

Frequently asked questions

Is it true that jaundice always clears up within a week? Not always, and it isn't safe to assume this. Many babies do improve within the first week, but the right timeframe depends on your individual baby, and jaundice lasting into the second or third week, or appearing after a jaundice-free period, needs its own assessment rather than an assumption that it will simply pass.

Can I just check my baby's bilirubin at home or wait it out? No — bilirubin levels need proper equipment to measure accurately, and interpreting them safely depends on your baby's precise age in hours, gestational age, and individual risk factors. This is a clinical assessment, not something to estimate at home.