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The fetus and newborn are uniquely vulnerable to serious infection. While the amniotic cavity affords substantial protection against pathogens, fetal infection by viruses, bacteria, or parasites can occur throughout pregnancy. Infection can also begin during parturition, which entails sudden and simultaneous contact with a variety of potential pathogens, or from postnatal exposure to colonized skin, breast milk, or contaminated environmental surfaces.

The cumulative risk from these exposures is compounded by the compromised immunity of the neonatal host. Both innate and adaptive immunity are impaired during the newborn period, setting the stage for infections that are unusual later in childhood. Furthermore, functional immunodeficiency limits the newborn’s ability to contain infection within a single anatomic site. As a consequence, neonatal infection often presents as a systemic disease affecting multiple organ systems simultaneously. Clinicians in the nursery and newborn clinic must therefore maintain a high level of suspicion. When confronted with an ill neonate, the clinician must initially rank infection high on the list of differential diagnoses.

Newborn infections can be categorized into three categories on the basis of the time of presentation, reflecting different mechanisms of pathogenesis and—to some extent—different pathogens. These categories are as follows:

  1. Congenital. Infection present at birth, due to vertical (maternal-to-fetal) transmission of the infection through hematogenous, transplacental passage or ascending transit of cervicovaginal microorganisms.

  2. Early onset. Infection developing during the first 72 hours of life, resulting from intrapartum pathogenesis.

  3. Late onset. Infection presenting after 72 hours of life, due to postnatal exposure. (Note that some studies use 7 days rather than 72 hours as the cutoff between early-onset and late-onset infection.)

The most common infections for each period are presented in Table 54-1.

TABLE 54-1Common Newborn Infections Categorized by Age at Onset

This chapter reviews key concepts in the epidemiology, pathogenesis, evaluation, and management of infants in the nursery with perinatal infectious exposures. Congenital (“TORCH”) infections are discussed in Chapter 53, while neonates presenting for evaluation of fever are discussed in Chapter 55.



Bacteremia that occurs within the first 3 days of life is termed early-onset sepsis (EOS). ...

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