Newborn Jaundice: What Is Normal and When to Worry

On day three the midwife came round for her home visit and held my baby up to the window. "She's a bit yellow," she said, in the same voice she might have used to mention the weather. "Probably nothing. Just watch her colour over the next 48 hours."

I spent the next 48 hours staring at my baby in different light. Was that the yellow she meant? Was she more yellow than yesterday or just sleepier? Was the yellow now on her chest, which the leaflet said was the line to worry about? I googled "newborn jaundice" 47 times and every result told me a slightly different version of when to panic.

If you are at this point with a slightly yellow baby, here is the version I wish I had read instead of the leaflets. What is genuinely normal, what is not, and the specific signs that mean stop scrolling and call your GP now.

Why most newborns turn yellow

Newborn jaundice happens because of bilirubin, a yellow pigment that the body makes when it breaks down old red blood cells. Adults get rid of it through the liver and out in poo. Newborns are born with extra red blood cells (they needed them in the womb), and their liver is not yet fully online to process the bilirubin fast enough. The leftover pigment shows up as a yellow tint in the skin and the whites of the eyes.

About 6 in 10 full-term newborns develop some visible yellowing in the first week. For breastfed babies, the number is even higher, because breast milk takes a little longer to set up regular pooing, which is the main route bilirubin leaves the body. For premature babies, it is higher still.

The peak is usually somewhere between day three and day five. For most babies, it then fades on its own over the next week or two. Nothing needs to be done.

What "normal" jaundice actually looks like

Mild jaundice has a few telltale signs:

The yellow starts on the face and forehead first, sometimes the whites of the eyes
It is more obvious in natural daylight, especially when you press gently on the skin and the spot stays yellow as the blood blanches away
The baby is feeding well, pooing and weeing regularly, and seems content between feeds
The skin colour stays roughly stable or improves over time

If your baby ticks all of those, you are almost certainly in the normal category. Keep feeding, keep watching, and the colour will probably fade in 10 to 14 days.

What "not normal" jaundice looks like

The line between watch-and-wait and call-someone-today is not a vibe. It is a checklist. Any of these means you should call your GP, midwife, or health visitor the same day. Not next week. Today.

The yellow has spread from the face down to the chest, belly, arms, or legs
The whites of the eyes are visibly yellow, not just slightly tinged
The baby is unusually sleepy, hard to wake up for feeds, or floppy when you pick them up
The baby is not feeding well or refusing the breast or bottle
Fewer than 6 wet nappies in 24 hours after day five
Fewer than 3 dirty nappies a day by day four
The cry has gone high-pitched or sounds different from normal
The baby is arching their back in an unusual way during crying
Jaundice that is still very visible after 14 days for breastfed babies, or after 10 days for formula-fed babies
Jaundice that appears in the first 24 hours of life (this is always abnormal, regardless of how mild it looks)

The last two are the ones most leaflets do not explain clearly. Jaundice in the first 24 hours is never normal physiological jaundice, because the bilirubin should not have built up that fast. It usually means something specific is going on, often a blood group incompatibility between mum and baby (like ABO or Rhesus incompatibility, where mum's antibodies attack the baby's red blood cells). It is usually treatable but needs same-day investigation.

Why kernicterus is the word nobody mentions but everyone is worried about

The reason hospitals and midwives take jaundice so seriously is not that yellow skin is dangerous. It is that very high bilirubin levels, left untreated, can in rare cases cross into the brain and cause a condition called kernicterus (a type of brain damage caused by very high bilirubin levels in newborns, where the pigment crosses into and stains brain tissue, particularly the area that controls movement).

Kernicterus is rare. We are talking maybe 1 in 100,000 births in countries with routine newborn screening. It is also entirely preventable when jaundice is identified and treated in time. The whole point of the bilirubin test (the little heel-prick blood test or the light-meter forehead test) and the warning sign checklist is to catch the very small number of babies who are heading toward dangerous levels and start treatment before any harm is done.

So when a leaflet sounds dramatic, this is what they are quietly trying to prevent. Not the yellow skin. The very rare worst-case scenario.

How jaundice is actually treated

For most babies, the answer is "more feeding." Breast milk or formula stimulates pooing, and pooing clears bilirubin from the body. Feed more often, especially in the first week. If you are breastfeeding and your milk has not fully come in yet, ask your midwife whether top-ups of expressed milk or formula are appropriate to get more volume in.

For babies with bilirubin levels above a treatment threshold (determined by their age in hours and their weight, plotted on a curve called the bilirubin chart), the next step is phototherapy. This is the special blue light treatment you may have heard about. The baby lies under or wrapped in a blanket of LED lights that emit a specific blue wavelength. The light breaks down bilirubin in the skin into a form the baby can pee out without needing the liver. It is gentle, painless, and dramatically effective. Most babies need it for 1 to 3 days. They go home with mum the whole time in many hospitals now via portable units.

For very high bilirubin levels, or for jaundice caused by blood incompatibility, more intensive treatment exists (such as IV immunoglobulin or in extremely rare cases an exchange transfusion). These are uncommon and only used when the curve shows the level is climbing fast.

What to do tonight

If your baby is mildly yellow but feeding well, pooing, weeing, and waking for feeds:

Feed often. Aim for at least 8 to 12 feeds in 24 hours in the first week
Get some natural daylight in the room during the day. Open the curtains. (Direct sunlight on a newborn through a window is not recommended because of the heat risk, but bright indirect daylight is fine and may help slightly.)
Check the colour in natural light at the same time each day, not in the lamplight
Press gently on the skin of the chest. If the spot turns yellow as the blood blanches, that is a sign jaundice has spread past the face
Call your midwife or health visitor team if anything from the warning signs list applies

If your baby is more than mildly yellow, sleepy, or feeding poorly, call your GP or midwife today. They will likely want to see the baby and may run a bilirubin test. Do not wait for the next routine appointment. Same day matters with jaundice.

What to tell yourself at 3am

The fact that you are watching your baby's colour so carefully is exactly what catches the small number of cases that need treatment. You are not being neurotic. You are doing the job.

Most yellow babies stay mildly yellow for a week or two and then are fine. A small number need a couple of days of light treatment and then are fine. A very small number need more intensive care and almost all of them are still fine afterwards because of the screening systems that exist.

The leaflets sound scary because the worst-case scenario is genuinely serious. The reality is that the worst case has been made extremely rare precisely because mums like you check the colour every morning, ring the GP when something feels off, and feed the baby every two hours through tiredness that does not feel survivable.

Keep feeding, keep watching, call when in doubt. Your instinct that something is not quite right is the most accurate test there is.

Newborn Jaundice: What Is Normal and When to Call Your GP