Neonatal sepsis is a bacterial infection in the blood. Early-onset sepsis develops in the first 2 to 3 days after birth. Late-onset sepsis develops within 3 to 7 days after birth.

Spread of Infection
infant sepsis

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Neonatal sepsis is caused by bacteria.

Early-onset sepsis is caused by an infection from the mother. It may pass to the infant from the placenta or birth canal during birth. Late-onset sepsis is caused by bacteria from the healthcare environment.

Risk Factors

This problem is more common in babies that are:

  • Male
  • Born very early
  • Born with a low birth weight

Other things that may raise the risk are:

  • A mother whose water broke more than 18 hours before giving birth
  • Group B streptococcal bacteria in the mother's vaginal or rectal areas
  • Babies that need early care, such as a catheter


Symptoms may be:

  • Fever or many changes in temperature
  • Problems feeding
  • Fussiness
  • Lack of energy
  • A high-pitched cry
  • Yellow, blue, or pale skin
  • Bruising or bleeding
  • Cool, clammy skin
  • Skin rashes
  • Fast breathing, problems breathing, or periods of no breathing
  • Vomiting
  • Diarrhea
  • Swollen belly
  • Little or no urination
  • Tremors


You will be asked about your baby's symptoms and health history. A physical exam will be done.

These tests will be done to look for signs of infection:

  • Blood tests
  • Urine tests
  • Lumbar puncture to check the fluid around the brain and spinal cord
  • Respiratory secretion testing


Treatment depends on how severe the problem is. It may include:

  • Antibiotics to treat infection
  • Supportive care, such as IV fluids
  • Oxygen or breathing support


Neonatal sepsis may be prevented by good prenatal care. This includes controlling any bacteria in the mother before it is spread during pregnancy or birth.


American Congress of Obstetricians and Gynecologists

Centers for Disease Control and Prevention


Health Canada

Sick Kids—The Hospital for Sick Children


Early-onset neonatal sepsis. EBSCO DynaMed website. Available at: Updated July 2, 2018. Accessed January 7, 2020.

Late-onset neonatal sepsis. EBSCO DynaMed website. Available at: Updated November 8, 2019. Accessed January 7, 2020.

Neonatal sepsis (sepsis neonatorum). The Merck Manual Professional Edition website. Available at: Updated July 2018. Accessed January 7, 2020.

Shane AL, Sánchez PJ, et al. Neonatal sepsis. Lancet. 2017 Oct 14;390(10104):1770-1780.

Last reviewed September 2019 by EBSCO Medical Review Board Kari Kassir, MD