Repeat instrumental delivery: how high is the risk?

The objective of this study was to investigate whether a history of previous instrumental delivery imposes a higher risk of operative delivery in subsequent pregnancies. The outcome of labour in 108 women with 1 previous instrumental delivery was compared to that of 216 randomly-selected controls delivered in the same period. There was no difference between these 2 groups of patients in maternal age, height, parity, gestational age, incidence of induction of labour, incidence of epidural analgesia, or birth-weight of the babies. The incidence of instrumental delivery was found to be 8.3% among the study group, which was significantly higher than that of 2.3% among the control cases (relative risk = 3.6, 95% CI 1.24 to 10.5). This increase in risk of operative delivery was independent to the indications for or the type of instrumental delivery in previous pregnancies. We conclude that women with 1 previous instrumental delivery are at a higher risk of repeat operative delivery. This may have implication in assessing patients for home delivery.