• neonatology
• infectious diseases

One of the most uncommon, life-threatening and feared issues newborn clinicians struggle to measure is the likelihood that a newborn has acquired a bacterial infection during the process of birth. Early-onset neonatal sepsis (EONS) occurs at a rate of 1/1000 to 1/2000 term-born infants in high-income areas such as the UK and the USA; most of those affected require neonatal intensive care, and 2%–3% die despite such care. The optimal approach to this low-incidence, high-consequence condition has vexed neonatal clinicians for decades. An understanding of the pathogenesis of EONS as ascending colonisation and invasion of the uterine compartment and fetus with maternal genitourinary and gastrointestinal flora informs specific risk factors for infection. The definitive diagnostic for EONS is isolation of a pathogenic species from blood or cerebrospinal fluid culture; this test requires adequate volumes of these fluids, and the answer is not available in most cases for 12–48 hours. Assuming that inflammation accompanies infection, laboratory tests such as the complete blood count (CBC), C reactive protein and procalcitonin are measured to predict the presence of infection before culture can confirm it. In USA, the Centers for Disease Control and Prevention and professional societies such as the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics provide guidance on how to approach risk of EONS. In the UK, the National Institute for Health and Care Excellence …