Authors Reply to "Induction of labour and emergency caesarean section in English maternity services: examining outcomes is needed before recommending changes in practice".

We thank Anna Seijmonsbergen-Schermers and colleagues for their interest in our paper in which we describe that there is considerable between-hospital variation in the use of induction of labour and emergency caesarean section in singleton term births that took place in the English National Health Service between April 2015 and March 2017.1 More importantly, we also show that hospitals with a higher rate of induction had slightly lower risks of adverse perinatal outcomes, whilst a similar association was not found for emergency caesarean section. In our paper, we suggest that the between-hospital variation observed in the induction of labour and emergency caesarean section rates may reflect differences in the ‘practice style’ of hospitals providing maternity services. Admittedly at the risk of over-interpreting our results, we conclude that a more proactive practice style with an increased use of induction of labour, rather than an increased use of caesarean section in emergency situations, seems to be linked to safer childbirth.

Seijmonsbergen-Schermers and colleagues raise two issues. First, they argue that the range of outcome measures we use, i.e., antenatal and intrapartum stillbirth, neonatal unit admission, and mechanical ventilation, is too narrow. They argue that perinatal mortality should have been used instead of stillbirth, because induction of labour may in some cases only change the timing of birth without preventing a baby dying in utero or at a later stage. We could not agree more. Indeed, the ideal study would have used perinatal mortality. However, it is important to note that in our paper we also show associations of induction of labour with better postnatal outcomes, e.g., lower neonatal admission and mechanical ventilation, which are fully in line with the associations that we report for stillbirth.

Second, Seijmonsbergen-Schermers and colleagues contrast our results with a population-based follow-up study they carried out using linked data reporting a range of outcomes in healthy women giving birth to a singleton term baby with and without induction of labour between 2000 and 2016 in New South Wales, Australia.2 They conclude that their results show that induction of labour for non-medical reasons was associated with more adverse perinatal outcomes. Here, we need to point out the fundamental difference between this study and the one that we report in our paper: we answer a different question with a different study design. We compare outcomes in hospitals with higher and lower rates of induction and emergency caesarean section; Our study does not directly compare a group of women who had induction of labour with a group of women who did not. Therefore, the studies are not directly comparable. Our study design, comparing perinatal outcomes according to hospital-level intervention rates, is likely to be less strongly affected by confounding by clinical indication than the population-based follow-up study by Seijmonsbergen-Schermers.

Most importantly, we wholeheartedly support Seijmonsbergen-Schermers’ final plea: projects aiming to get a better understanding of how we can make childbirth safer should include a range of measures and indicators, ideally covering both maternal and neonatal outcomes beyond the intrapartum period.3

References

1. Seijmonsbergen-Schermers A, Peters LL, Downe S, Dahlen H, de Jonge A. Induction of labour and emergency caesarean section in English maternity services: Examining outcomes is needed be fore recommending changes in practice. BJOG. 2022. https://doi. org/10.1111/1471-0528.17359
2. Gurol-Urganci I, Jardine J, Carroll F, et al. Use of induction of labour and emergency caesarean section and perinatal outcomes in English maternity services: a national hospital-level study. BJOG. Vol 129, 11:1899-1906
3. Dahlen HG, Thornton C, Downe S, et al. Intrapartum interventions and outcomes for women and children following induction of labour at term in uncomplicated pregnancies: a 16-year population-based linked data study. BMJ Open. 2021;11(6):e047040.
4. NMPA Project Team. National Maternity and Perinatal Audit: Clinical Report 2022. Based on births in NHS maternity services in England and Wales between 1 April 2018 and 31 March 2019. London: RCOG;2022.