YELLOWNESS (JAUNDICE) (Birth-2 Weeks) What is happening inside my baby's body? Jaundice simply means a yellow discoloration of the skin.
It is a description, like calling the sky blue.
Some degree of jaundice is extremely common - it occurs in more than half of all babies.
The cause of jaundice is elevated bilirubin, a yellow pigment produced naturally in the body.
Bilirubin is a normal waste product.
In the womb, the placenta does the job of removing waste from the body.
But after delivery, the liver removes bilirubin from the blood while the intestines get rid of excess bilirubin in the stool.
In a newborn baby, sometimes the liver is not yet fully functioning, so it cannot get rid of the bilirubin effectively.
The bilirubin may build up faster than the liver can break it down and the intestine can dispose of it in the stool.
Other times the baby is pooping too infrequently, giving the intestines time to reabsorb the bilirubin rather than poop it out.
And sometimes the bilirubin that normally exists within the cells is released into the bloodstream, overwhelming the liver with too much bilirubin and causing a buildup of bilirubin in the blood.
Any of these scenarios can lead to jaundice.
When the cause of jaundice is slow liver function, it can take a few days of life before the liver functions fully, helping to remove bilirubin and other waste.
In the newborn, therefore, bilirubin circulates in the bloodstream longer than usual, and this extra bilirubin causes the skin to look yellow.
When bilirubin is elevated because it is released from the cells into the bloodstream, this is usually a consequence of the destruction or death of red blood cells.
All red blood cells age and die; it is a normal process.
When this happens, the cells are broken apart by the spleen.
They release the substances that had been stored inside, including bilirubin.
About 1 percent of all red blood cells die every day, and after the first week of life, the body is equipped to deal with this.
In newborns, however, up to 5 or even 10 percent of the red blood cells can break open every day.
This happens especially when a baby and its mother have different blood types.
A mother can form antibodies to her baby's blood, and these antibodies can react against the baby's blood, "attacking" it as foreign.
This reaction is called Coombs' positive hemolytic anemia.
It causes large numbers of red blood cells to die and large levels of bilirubin to be released into the blood stream.
Because the liver is already working slowly, it can take an extra long time to clear all of this bilirubin out of the blood.
In these cases, babies can look very yellow very quickly! Babies of mothers with certain blood types (O-negative, O-positive, A-negative, B-negative, and AB-negative) will typically have their blood type checked at birth because the risk of Coombs' positive hemolytic anemia is much higher.
Another possible cause of jaundice is infection.
When bacteria infect the blood, red blood cells can break apart more easily, releasing excess bilirubin.
Infection can also impair liver function.
For the same reasons listed previously, babies with infections can look quite yellow.
Babies older than a week or two have other causes of jaundice, including liver disease.
Amazingly jaundice in babies usually starts in the face and makes its way down the body.
When it resolves, it moves in the opposite direction.
Therefore the whites of the eyes are usually yellow when the jaundice first begins, and they are the last part of the body to remain yellow until the jaundice completely resolves.
Jaundice may be more difficult to see in children of colour.
However, if the level is high and the jaundice is travelling down the body, then yellow discoloration can be visible in the palms and even soles of the feet.
In general, though, jaundice is more difficult to see in darker-skinned babies.