Birth to 3 months is perhaps the most vulnerable time in our lives. Baby's immunity is quite weak at this age, and they do not have much ability to localize and control infections. The signs and symptoms of illness are subtle in newborns, hence physicians have to extra sensitive in evaluating babies of this age.
Every effort should be made to avoid infections in newborns. People with cold and cough symptoms should maintain their distance with the babies if possible. If mother has a cold, she should wear a mask while breast feeding. No body should kiss the baby on the face. Our mouths have lots of bacteria which can be transmitted to the vulnerable newborn. If family members must kiss the baby, they should be told to kiss on the body instead of face. Make sure everybody washes their hands before touching the baby.
Fever in a baby less than 3 months of age is an emergency and must be promptly evaluated. Most probably the doctor will check your baby for serious infections with the help of blood and urine tests. A lumbar puncture or spinal tap may also be needed to evaluate for meningitis. Please take fever in a newborn seriously and seek medical attention promptly. It is best to keep a rectal thermometer at home for monitoring the exact temperature of the baby. Temperature of >100.4 degree Fahrenheit rectally is classified as fever in newborns. Remember that temperatures taken in the axilla and in the mouth may be an under estimate of true temperature in newborns. A video of how to take temperature in newborns is shown below.
Other danger signs in newborns include persistent inconsolable crying, breathing difficulty, refusal to feed such that the baby misses two feeds in a row, lethargy, diarrhea with associated dehydration and extreme irritability. Please seek prompt medical attention if you observe these signs in your newborn.