RESUMO
It is vital to determine whether a fetus is showing a normal physiological response to the stress of labour or if the fetus is exposed to intrapartum hypoxia to ensure timely and appropriate management. Failure to interpret fetal heart rate correctly during second stage of labour may lead to increased maternal and neonatal morbidity due to an unnecessary caesarean section or an instrumental vaginal delivery. Conversely, delay in timely and appropriate intervention can also result in increased perinatal morbidity and mortality. This review addresses the pathophysiology behind features observed on the CTG trace as well as the types of intrapartum hypoxia during second stage of labour and aims to identify common pitfalls including inadvertent monitoring of maternal heart rate as well as monitoring and interpretation of cardiotocograph of twin pregnancies in the second stage of labour.