Pathophysiology of Neonatal Sepsis Early-onset neonatal sepsis Certain maternal perinatal and obstetric factors increase risk, particularly of early-onset neonatal sepsis, such as the following: Premature rupture of membranes (PROM) occurring ≥ 18 hours before birth Maternal chorioamnionitis (most commonly manifesting as maternal fever shortly before or during delivery with maternal leukocytosis, tachycardia, uterine tenderness, and / or foul-smelling amniotic fluid) Colonization with GBS Preterm delivery Hematogenous and transplacental dissemination of maternal infection occurs in the transmission of certain viral (eg, rubella, cytomegalovirus), protozoal (eg, Toxoplasma gondii), and treponemal (eg, Treponema pallidum) pathogens. A few bacterial pathogens (eg, L monocytogenes, Mycobacterium tuberculosis) may reach the fetus transplacentally, but most are acquired by the ascending route in utero or as the fetus passes through the colonized birth canal.