'Kramer's rule'
The easiest (and most common) method a caregiver will use to monitor a baby for jaundice levels is to observe their physical appearance and behaviour. This is usually done on a daily basis.
The midwives on the postnatal ward in the hospital will look at the depth and extent of the yellow discolouration of the baby's body. They will also take note of the baby's alertness when they are awake, and their desire or eagerness to feed. If you are at home in the first week (or had a homebirth), your midwife visiting you daily will observe your baby. If you go home from the hospital after 3 or 4 days, but are concerned about your baby being jaundiced, you should contact your caregiver, or return to the hospital, so that your baby can be checked.
Kramer's rule. There is an old, but fairly reliable, method that a caregiver can use to estimate the level of bilirubin in a baby before they consider ordering a blood test. The method uses 'Kramer's Rule' and is based on the caregiver gently pressing various areas of the baby's skin with their fingertip. The pressure 'blanches' the baby's skin (or momentarily shifts the blood supply from under the skin) so that the caregiver can see how 'white' or 'yellow' the skin looks. The examination must be carried out in good lighting conditions and may not be as effective with darker skinned babies.
Kramer's Rule is based on the way the jaundice will tend to 'migrate' down the baby's body, as the bilirubin levels rise. In essence the baby's body is categorised into 5 zones with an estimated bilirubin level for each zone. If the jaundice is believed to be 200 to 250 imol / litre or more then a blood test would be used to estimate the exact bilirubin level.