No, newborn jaundice by itself doesn’t cause fever; a temperature of 38 °C (100.4 °F) points to another issue and needs same-day medical care.
Yellow skin in the first days of life is common. That color comes from bilirubin, a pigment the body clears through the liver. When levels rise faster than the liver can clear them, the skin and eyes look yellow. That’s newborn jaundice.
Parents often see the yellow tint and worry about heat or infection. The two can appear in the same week, which adds to the confusion. The short answer: jaundice doesn’t trigger a fever. Fever usually comes from an infection or another illness that needs a clinician to check the baby.
You’ll find clear guidance in the American Academy of Pediatrics’ parent site and the NHS advice for babies under three months. Both stress a simple rule: any temperature of 38 degrees Celsius or higher in a young baby needs urgent assessment.
What Newborn Jaundice Is
Most babies develop a mild rise in bilirubin around day two to four. This is called physiologic jaundice. Red blood cells break down, the newborn liver is still maturing, and the gut reabsorbs some bilirubin. The result is a harmless yellow tint that fades over a week or two.
Other patterns exist. Breastfeeding jaundice appears in the first week when intake is low, then improves as feeds pick up. Breast milk jaundice appears after the first week and can last longer while the baby stays well. Early jaundice in the first 24 hours, deep yellow color, or jaundice with poor feeding needs a prompt visit.
Here’s a quick map of common jaundice types and whether fever belongs with them:
| Jaundice Type | Usual Timing | Does It Cause Fever? |
|---|---|---|
| Physiologic jaundice | Day 2–4; fades in 1–2 weeks | No. Fever points to another cause. |
| Breastfeeding jaundice | First week with low intake | No. Improve feeds; check weight and hydration. |
| Breast milk jaundice | After week 1; baby otherwise well | No. Temperature should be normal. |
| Hemolysis (Rh/ABO, G6PD) | Often in the first 24–48 hours | Not by itself. Needs blood tests and close follow-up. |
| Infection-related jaundice | Any time in the neonatal period | Fever can occur from the infection; jaundice is a companion sign. |
| Cholestasis/biliary atresia | After 2 weeks with pale stools, dark urine | Fever isn’t typical; stool color is the key clue. |
Can Newborn Jaundice Cause A Fever? Myths Vs Facts
Fever is a core body temperature of 38 degrees Celsius, or 100.4 degrees Fahrenheit. Bilirubin doesn’t raise temperature. When fever shows up with yellow skin, something else is going on. In the first days, that “something else” is often an infection, a urinary tract problem, or another condition that also happens to cause jaundice.
Think of jaundice as a sign you can see, while fever is a sign you can measure. The two might travel together by coincidence, not cause and effect.
When Fever And Jaundice Show Up Together
Doctors look for infections first. Newborn sepsis can appear with fever, sleepiness, poor feeding, or low temperature. The urine can be a source as well. If a baby under three months has a fever, the safest plan is to get medical care the same day.
Blood group incompatibility, G6PD deficiency, or bruising from birth can push bilirubin up fast. These conditions don’t cause fever by themselves. A clinician will ask about timing, feeding, urine color, and stool color to sort the picture.
Red Flags That Need Care Now
- Jaundice in the first 24 hours after birth.
- Temperature at or above 38 °C (100.4 °F) measured with a rectal thermometer.
- Poor feeding, weak suck, or fewer than six wet nappies in 24 hours after day four.
- Dark urine that stains the nappy or pale, chalky stools after the first week.
- A very sleepy baby who is hard to wake or has a high-pitched cry.
- Yellow color spreading to the arms, legs, and palms.
How Clinicians Check A Jaundiced Baby
The exam starts with the baby’s weight, hydration, and a careful look at skin and eyes. A light meter on the skin can estimate bilirubin. If the number is near a treatment threshold, a blood test confirms the level. The lab also checks the baby’s blood type, a direct antiglobulin test, and sometimes a screen for G6PD deficiency.
If fever is present, staff may take blood and urine for cultures and, in some cases, do a lumbar puncture. The goal is to find or rule out infection while treating any high bilirubin at the same time.
Phototherapy And Temperature
Phototherapy uses blue light to change bilirubin so the body can clear it. The lights can feel warm, yet they aren’t meant to cause fever. Staff monitor temperature and hydration during treatment. If the baby gets too warm, they adjust the setup or take a break. True fever still points to another cause.
Safe Temperature And Action Plan
A reliable rectal thermometer gives the best reading in young babies. Armpit thermometers can read low. If you use one and the number is near 38 °C, recheck by rectum. Dress your baby in a single layer, feed often, and keep the room comfortable. Don’t sponge with cold water or place the baby in direct sun.
Use this table to decide the next step if you see yellow skin and you’re checking temperature at home:
| Baby’s Age | Temperature Reading | Action |
|---|---|---|
| Under 3 months | 38 °C (100.4 °F) or higher | Seek same-day medical care. Don’t give fever medicine unless told to. |
| Under 3 months | 36.5–37.5 °C (97.7–99.5 °F) | Normal. Keep feeds frequent. Keep baby clothed and comfortable. |
| Any age in the first month | Low temperature below 36.0 °C (96.8 °F) | Warm the baby and call for advice. This can signal illness. |
Feeding, Hydration, And Stool Clues
Good intake helps remove bilirubin through the gut. Aim for 8 to 12 feeds in 24 hours in the early days. Waking for feeds is fine. Wet nappies should rise daily, reaching six or more by day four. A baby who latches well and gains weight tends to clear jaundice faster.
Urine should look pale. Very dark urine can mean extra bilirubin passing through the kidneys. Stools should turn mustard or green by the end of the first week. Pale or white stools are not normal and need a same-day call.
Preventing Severe Jaundice
A newborn check within three to five days after birth catches rising bilirubin at the usual peak. Earlier follow-up is common for babies with risk factors such as prematurity, bruising, a sibling treated for jaundice, or a different blood type than the mother.
- Set up the first newborn visit before leaving the hospital.
- Feed early and often, and ask for lactation help if latching hurts or sessions are short.
- Know your baby’s blood type if testing was done, and share any family history of G6PD deficiency or severe jaundice.
- Use the care team’s bilirubin result and follow the plan for any repeat checks.
Common Myths And Quick Facts
A few ideas keep circulating in family chats. Here’s what the evidence supports:
- “Sunbathing treats jaundice.” Sunlight is hard to dose and risks sunburn. Use only the lights your team sets up.
- “Yellow eyes mean a liver disease.” In healthy newborns the liver is still maturing. Jaundice that lasts beyond two weeks, or pale stools, needs a review.
- “Phototherapy causes fever.” The lights can warm skin, yet real fever points to something else and needs a check.
- “Formula is the only fix.” Many breastfed babies clear bilirubin with frequent, effective feeds. Your clinician may suggest supplements in some cases.
Bottom line: jaundice is common, fever is not part of it, and a temperature of 38 °C or higher in a baby under three months needs same-day care. Trust your instincts and get help early if anything feels off.