We investigated antepartum and intrapartum risk factors for neonatal encephalopathy (NE) in term infants. We performed a case-controlled study in which characteristics of singleton term infants who developed NE from 1993 to 2003 were compared with those of randomly selected controls. Antenatal risk factors (including obesity, diabetes, thyroid dysfunction, previous cesarean delivery, preeclampsia, fetal growth restriction, abnormal amniotic fluid volume, and abnormal fetal heart rate [FHR] tracing before labor) and intrapartum risk factors (acute intrapartum sentinel events and other risk factors like suspicious or ominous FHR tracing and clinical chorioamnionitis) were related to occurrence of NE. From the study cohort of 30,580 infants, 27 (0.09%) developed NE and were compared with 100 controls. Neonates with encephalopathy had more frequent antepartum (74% versus 18%, P < 0.001) and intrapartum (67% versus 19%, P < 0.001) risk factors, including acute intrapartum events (33% versus 2%, P < 0.001), than controls. On the whole, 26% of cases of NE had only antepartum risk factors, 22% had only intrapartum risk factors, and 44% had a combination of the two. In 2/27 (7%) cases, no risk factors were recognizable. In conclusion, 44% of cases of NE following term deliveries can be attributed to a combination of antepartum and intrapartum variables.
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