How your newborn's jaundice is protecting them from deadly sepsis, expert warns

JAUNDICE is a really common condition in newborn babies.

Around 80 per cent of premature babies are born with it as are up to 60 per cent of full-term infants.

And it can be dangerous.

Jaundice can lead to conditions like acute bilirubin encephalopathy, which damages the infant's brain and causes developmental problems.

But now scientists from the Universities of Glasgow and Aberdeen, and UNSW Syndey believe that jaundice may also be an important defense against deadly sepsis.

Writing for The Conversation, Richard Hansen, Elaina Collie-Duguid and Georgina Hold explain how jaundice may be a good thing:

When most people think of jaundice, they probably think of yellow skin.

This is caused by too much of an orange-yellow pigment known as bilirubin in the blood. Bilirubin is released when old red blood cells are being broken down.

Normally it travels to the liver before being excreted in poo and urine, but this process can go wrong when there has been some upset to the liver that prevents it from doing its job properly.

In adults, this can be a sign of underlying conditions ranging from hepatitis to alcoholic cirrhosis.

With newborns, the situation is slightly different: the body needs to make the transition from fetal to adult blood, but the liver does not yet have the capacity to cope with the bilirubin released in the turnover of red blood cells.

The resulting jaundice usually passes uneventfully.

Why do we still get jaundice?

Why haven't humans evolved to overcome this temporary bilirubin problem?

Richard started wondering about this when he was doing his PhD in gut microbiology at the University of Aberdeen, while regularly working on call at the neonatal unit as a registrar at the city’s maternity hospital.

One night he was looking after a baby boy who had sepsis, which is where the immune system goes into overdrive to protect against infection, potentially leading to severe inflammation, organ failure and death.

Symptoms of newborn jaundice

Jaundice usually appears about 3 days after birth and disappears by the time the baby is 2 weeks old.

In premature babies, who are more prone to jaundice, it can take 5 to 7 days to appear and usually lasts about 3 weeks.

It also tends to last longer in babies who are breastfed, affecting some babies for a few months.

If your baby has jaundice, their skin will look slightly yellow. The yellowing of the skin usually starts on the head and face, before spreading to the chest and stomach.

Changes in skin colour can be more difficult to spot if your baby has a darker skin tone.

In these cases, yellowing may be more obvious elsewhere, such as:

  • in the whites of their eyes
  • inside their mouth
  • on the soles of their feet
  • on the palms of their hands

A newborn baby with jaundice may also:

  • be sleepy
  • not want to feed or not feed as well as usual
  • have dark, yellow pee (it should be colourless)
  • have pale poo (it should be yellow or orange)

Source: NHS

This baby was profoundly unwell in intensive care, suffering from inflammation and a strikingly high bilirubin count that was only just being controlled with three phototherapy lamps.

Usually, this kind of difficult jaundice is caused by an immune reaction between mum’s and baby’s blood groups, but not in this case.

Richard began wondering if the bilirubin was directly linked to the infection, and if it was part of the baby’s body’s attempt to clear the sepsis (in this case the baby survived).

Humans evolved to fight off infection

He started thinking about the problem in evolutionary terms – if jaundice can harm the baby, what benefit does it offer to balance this?

Thinking about babies in caves in days gone by, with no healthcare and certainly no antibiotics, Richard realised that the biggest threat to their life after surviving delivery would probably be overwhelming sepsis in the first few days – exactly when the bilirubin level rises naturally.

Could jaundice be an evolutionary mechanism to protect against this?

Richard got to work with an 11-strong team at the University of Aberdeen and NHS Grampian, recruiting a willing medical student to spend his summer holiday working with blood plates, bilirubin and bacteria grown originally from neonatal blood cultures taken from septic babies.

Proof jaundice helps fight sepsis

Our team has now shown that even modest concentrations of bilirubin reduced by one third the growth of Streptococcus agalactiae.

We also showed that bilirubin may alter substrate metabolism in the bacteria.

We now need to do more work, probably in animal experiments of sepsis.

This will enable us to think about whether clinicians should raise the accepted bilirubin threshold for babies at risk of sepsis – those born prematurely, for example.

It feels like we’re discovering something new about the physiology of newborn babies.

When newborn babies develop jaundice in future, we’ll still need to treat it carefully.

But quite possibly we will also be thankful that it’s protecting them from something potentially life-threatening.

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