Success rate of repeated cycles of induction in labour in a UK clinical setting: A cohort study

Background: : Births are increasingly started artificially using medications such as prostaglandin, oxytocin, or other mechanical methods, a process known as induction of labour (IOL). The aim of the study was to identify the success rate of a repeat cycle of induction of labour (IOL) with prostaglandins, and any association between smoking and patient response to prostaglandin. Methods: : This was a retrospective cohort study set in Basildon and Thurrock University Hospital, UK.  IOL data from patients were collected between 1 January 2021 and 30 March 2021. Data were retrieved from hospital records and categorised by prostaglandin cycle(s), administration of oxytocin, artificial rupture of membranes (ARM), spontaneous rupture of membranes (SROM), smoking status, patient BMI, age, ethnicity, gestation age, Bishop score, and delivery method (assisted, unassisted, or Caesarean (C-)section). The data were analysed using Chi-square, binomial and multinomial logistic regression. The success rate was interpreted from relative frequencies of delivery method (unassisted, assisted or C-section). Results: : Unassisted vaginal delivery (n =121; 48.0%) was the most common outcome with prostaglandin IOL followed by C-section (n = 105 41.7%). Only 10.3% had an assisted vaginal delivery. Of those who had a repeated IOL cycle, 85.7% had a C-section. There was no difference in prostaglandin administration by smoking status or any association between smoking status and mode of delivery in IOL. Conclusions: : Repeat cycle of IOL does not enhance the vaginal delivery with only 14.3% unassisted vaginal births. There was no evidence that smoking impacted on response to prostaglandins or method of delivery.