Signs of Infection and Sepsis in Newborns
The short answer
Neonatal sepsis is a serious bacterial infection in the bloodstream that can develop in the first month of life. Signs are often subtle and can include temperature instability, poor feeding, lethargy, irritability, rapid breathing, and a "just not right" appearance. Neonatal sepsis is a medical emergency requiring immediate antibiotics. Trust your instincts if your newborn seems unwell.
Parents everywhere have the same worry. You are doing the right thing by looking into it.
By Age
What to expect by age
Neonatal sepsis is classified as early-onset (within the first 72 hours, usually from bacteria acquired during delivery) or late-onset (after 72 hours, from environmental or hospital-acquired bacteria). Signs can be subtle and include: temperature instability (fever OR low temperature), poor feeding or refusal to eat, lethargy or excessive sleepiness, irritability, rapid breathing, grunting, apnea (breathing pauses), jaundice, vomiting, abdominal distension, and rash. A key warning sign is when parents say the baby "just doesn't seem right." Any suspicion of sepsis requires immediate emergency evaluation with blood cultures and empiric antibiotics while awaiting results.
Infection risk remains elevated in the first 3 months because the immune system is still immature. Late-onset sepsis can occur from urinary tract infections, meningitis, or other bacterial sources. Any fever (100.4F or higher) in a baby under 3 months requires emergency evaluation. Signs of infection at this age are similar to the newborn period.
While the risk of life-threatening bacterial infection decreases somewhat after 3 months, serious infections can still occur. Fever is taken seriously and evaluated, though the approach may be less aggressive than in younger infants depending on how the baby appears.
Older infants have a more mature immune system but can still develop serious infections. Signs of illness are usually more apparent at this age. Trust your instincts if your baby seems significantly unwell.
What Should You Do?
When to take action
- There are no "normal" signs of sepsis. All concerns about potential infection in a newborn should be taken seriously.
- Your newborn seems slightly off but you cannot pinpoint what is wrong
- Feeding seems less vigorous than usual
- Your baby is sleepier than normal or more fussy than typical
- Any fever (100.4F/38C or higher rectally) in a baby under 3 months old requires emergency evaluation immediately
- Baby is lethargic, has a weak cry, refuses to feed, has rapid or labored breathing, or you feel something is "just not right"
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Medical Concerns
Fever in a Baby Under 3 Months Old
A fever in a baby under 3 months old (temperature of 100.4 degrees F / 38 degrees C or higher taken rectally) is always a medical emergency. Go to the emergency room immediately, regardless of how well your baby appears. Young babies' immune systems cannot fight infections as effectively as older children, and a fever could indicate a serious bacterial infection (urinary tract infection, bacteremia, or meningitis) that needs urgent treatment. Do NOT wait to see if the fever goes down. Do NOT give fever medication and stay home - go to the ER first.
Group B Strep (GBS) Infection in Newborns
Group B Streptococcus (GBS) is a bacterium that some mothers carry and can pass to their baby during delivery. When mothers who test positive receive antibiotics during labor, the risk to the baby is greatly reduced. GBS infection in newborns can be serious, causing sepsis, pneumonia, or meningitis, but with prevention measures and prompt treatment, most babies do well.
When to Call Your Pediatrician
Knowing when to call your pediatrician can be stressful, but a good rule of thumb is: if something about your baby worries you, it is always okay to call. In general, any fever in a baby under 3 months, difficulty breathing, signs of dehydration, or a sudden change in behavior warrants a prompt call. Trust your instincts - you know your baby best, and pediatricians expect and welcome these calls.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.
Adenoid Hypertrophy and Breathing
Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.