A temperature of 98.7°F is not a fever for a baby. It falls well within the normal range. A fever in infants is defined as a rectal temperature of 100.4°F (38°C) or higher, so 98.7°F sits nearly two full degrees below that threshold.
Normal body temperature for a child centers around 97.8°F (36.6°C), and it naturally fluctuates throughout the day. A reading of 98.7°F is a completely typical variation, not a sign of illness.
What Counts as a Fever in Babies
The widely accepted cutoff is 100.4°F (38°C) taken rectally. This is the standard used by the Mayo Clinic, the American Academy of Pediatrics, and most pediatric guidelines worldwide. Temperatures below that line, including readings in the 99°F range, are generally considered normal fluctuations rather than true fevers.
A baby’s temperature can shift by about a degree over the course of a day. It tends to be lowest in the early morning and highest in the late afternoon or evening. Activity, feeding, crying, and even a warm bath can nudge the number up temporarily. So if you check your baby’s temperature and see 98.7°F, there’s no reason for concern based on that number alone.
Why the Measurement Method Matters
Where you take the temperature affects the number you see. Rectal readings are considered the gold standard for babies because they most accurately reflect core body temperature. Ear (tympanic) and forehead (temporal artery) thermometers are also reliable and use the same 100.4°F fever threshold.
Armpit (axillary) readings, on the other hand, tend to run lower than rectal readings. If you got 98.7°F from an armpit thermometer, the actual core temperature could be slightly higher, but still well within normal range. For babies under 3 months old, a rectal thermometer gives the most trustworthy result when accuracy matters most.
Can Clothing or Warmth Raise the Reading?
Parents often wonder if bundling a baby could push the temperature up. Research on babywearing found that 15 minutes of skin-to-skin contact in a carrier raised babies’ skin temperature by up to 1.1°C (about 2°F) in areas like the abdomen, where the baby’s body pressed against the parent. However, the babies’ core temperature, measured at the ear, did not change. Adding an extra layer of light clothing didn’t make a difference either.
So while overdressing can make a baby’s skin feel warm to the touch, it’s unlikely to produce a falsely elevated reading on a rectal or ear thermometer. If your baby feels warm but the thermometer says 98.7°F, the thermometer is giving you the more accurate picture.
Teething and Slight Temperature Bumps
Teething is another common reason parents check temperatures. A 2011 study that tracked 47 babies daily for eight months found slight temperature increases on the day a tooth erupted and the day before, but none of the increases reached the 100.4°F fever threshold. If your baby is drooling, fussy, and reads 98.7°F, teething could explain the mild warmth you’re feeling, but 98.7°F is still a normal temperature. A reading of 100.4°F or above during teething likely points to an infection rather than the tooth itself.
When a Fever Does Need Attention
Age is the single biggest factor in how seriously to take a fever. For babies under 8 weeks old, any rectal temperature of 100.4°F or higher needs prompt medical evaluation. At that age, a baby’s immune system is still immature, and infections can progress quickly. The American Academy of Pediatrics lays out detailed evaluation protocols for febrile infants in the first two months of life, reflecting how seriously clinicians treat even well-appearing babies with confirmed fevers in this age group.
For older infants and toddlers, a fever alone isn’t always an emergency. What matters more is how the baby looks and behaves. Signs that warrant a call to your pediatrician alongside a fever of 100.4°F or higher include:
- Unusual drowsiness or difficulty waking
- Extreme fussiness that can’t be comforted
- Breathing difficulty
- A stiff neck, unexplained rash, or repeated vomiting and diarrhea
- Exposure to extreme heat, such as a hot car
None of these concerns apply at 98.7°F. That reading is normal, and your baby’s temperature is exactly where it should be.