The epidemiology of FIRS in term and late preterm births

The definition of FIRS requires systemic inflammation and elevated levels of IL-6 in fetal plasma. That definition does not specify how systemic inflammation is to be recognized, and perinatal measurement of IL-6 is not a standard procedure. FIRS has not been examined in a population-based study that included post-neonatal outcome so its incidence and natural history are not known. The overlap, and similarities and differences, of FIRS as compared with other causes of neonatal encephalopathy, and how these relate to findings in the placenta, have not been jointly examined in a generalizable sample. FIRS has chiefly been discussed in the obstetric literature because of the need for decisions about management of delivery and antibiotic use. If the term "FIRS" is to be employed in other contexts, consensus should be sought as to which clinical, placental, and laboratory findings are most appropriate for identification of perinatal inflammatory processes, infectious or sterile.