Background We report a case of congenital heart block presenting as a profound persisting bradycardia, leading to emergency delivery of a pre-term fetus. With no definitive pathogenesis identified in this scenario, we discuss potential underlying pathologies of neonatal heart block and their proposed management. We also consider the implications for subsequent pregnancies in this mother.

Case On admission a 35-week parous woman, found to have a persisting fetal bradycardia, was delivered by emergency Caesarean section. Although delivered in good condition, at five minutes of birth the neonate suffered a respiratory arrest associated with a profound bradycardia, requiring admission to the special care baby unit. An electrocardiogram demonstrated a second degree heart block but an echocardiogram revealed no structural abnormalities and the maternal autoimmune screen was negative. Histopathological examination of the placenta demonstrated a plasma cell deciduitis consistent with chronic uterine infection or autoimmune disease.

Discussion Here, an intrinsic bradyarrhythmia was interpreted, within the clinical context, as an acute event and managed with immediate delivery. Retrospectively, it is difficult to ascertain whether premature delivery compounded the neonatal outcome. Fetal cardiac arrhythmias are seen in association with maternal auto-immune disease or fetal cardiac anomalies. These can frequently be managed conservatively with antenatal surveillance by fetal echocardiography. In these circumstances, appropriate antenatal treatment can be initiated and the degree of paediatric input required for a planned delivery anticipated; as well as the need for ongoing support for the neonate.