The journey from induction to birth and beyond

Misoprostol, a synthetic analogue of prostaglandin E1, was approved in 1988, for the prevention and treatment of peptic ulcers associated with the use of nonsteroidal anti-inflammatory drugs. It is hard to believe that a drug initially used by gastroenterologists could become a crucial medication in obstetric practice. Misoprostol's versatility in administration, affordability, efficacy, relative safety and easy storage have contributed to its popularity. In 1987, the first studies on the off-label use of misoprostol for pregnancy termination, medical evacuation of missed abortions and as a cervical-priming agent prior to vacuum aspiration of the uterus started being published. These were followed by studies on its use for mid-trimester termination of pregnancy, management of intra-uterine fetal death, third stage of labour, induction of labour and post-partum haemorrhage.¹ It wasn't until nearly 15 years later that the FDA finally approved a new label addressing the use of misoprostol during pregnancy. This was followed by a number of trials demonstrating that misoprostol is at least as safe and effective as dinoprostone, the previous most popular agent for labour induction.² In this issue of BJOG (pages 1167-1180) Patabendige et al. conducted an individual participants' data meta-analysis of randomised controlled trials comparing the use of vaginal misoprostol and dinoprostone for the induction of labour. They concluded that both methods of labour induction were comparable in terms of effectiveness and perinatal safety as well as mode of delivery including vaginal, instrumental or Caesarean birth performed for failure to progress or fetal distress, supporting the non-inferiority of vaginal misoprostol.

Approximately, 30% of women in the UK and US deliver by Caesarean section^{3, 4} and at least 5% of these deliveries are performed in the second stage of labour. Full dilatation caesarean sections can be associated with significant maternal and neonatal complications, mainly due to extension of the uterine incision, resulting in haemorrhage, and birth injuries related to ‘impacted fetal head’; both of which are classified as obstetric emergencies. There is no consensus on the definition of ‘impacted head’ and consequently data on its incidence and guidance on the most effective and safest method of management, are lacking. Several management strategies including tocolysis, vaginal disimpaction (‘push’ method), breech extraction, Patwardhan method and use of the Fetal Pillow® have been employed. In 2022, a UKOSS prospective survey showed that the ‘push’ technique was the most commonly used technique to facilitate the delivery of the deeply engaged head, followed by the Fetal Pillow®.⁵ The Fetal Pillow® was first introduced in 2014 and initial small studies suggested a reduction in maternal and fetal complications. However, subsequent studies failed to demonstrate any significant improvement in perinatal complications and as a result, the National Institute for Health and Care Excellence (NICE) withdrew its support for the device, recommending further research before its introduction into clinical practice. Despite this, the Fetal Pillow® is now widely used worldwide. In the current issue (pages 1240-1248), Sadler et al. retrospectively investigated, the effect of the Fetal Pillow® on maternal and neonatal morbidity in two maternity units in New Zealand. They compared the rates of adverse outcomes before and after the introduction of the Fetal Pillow®, and between cases where the Fetal Pillow® was used, or not used despite being available. Despite the large number of births analysed, the study failed to demonstrate a significant difference in the risk of major uterine extensions or composite neonatal adverse outcomes in cases where the Fetal Pillow® was used (N = 375). Despite being retrospective, the study provides valuable insights into the use of this device in clinical practice. Only a randomised trial that compares various techniques for managing an impacted fetal head can provide definite answers to this complex problem. Until such a trial is undertaken, the use of high-fidelity simulation training, and the implementation of standardised management pathways, are likely to be the safest and most effective approach.

The management of fetal head impaction and caesarean section at full dilatation presents significant challenges, with potential negative impacts on maternal and neonatal health, including the increased risk of preterm labour in subsequent pregnancies. Unfortunately, there is no current consensus on the best way to deliver a pregnant person with prolonged second stage of labour. Beyond the immediate consequences, we need to consider the extent to which a prolonged second stage and the mode of delivery affect the pelvic floor function in the long term. Some (but not all) studies have associated a prolonged second stage with urinary and anal incontinence as well as pelvic organ prolapse. In the current issue (pages 1279-1289), Bergendahl et al. employed a population-based questionnaire to explore the impact of vacuum extraction and Caesarean section, in comparison to expectant management, on the pelvic floor function of primiparous women, 1–2 years following childbirth. This research focused specifically on birth complicated by prolonged (≥3 h) second stage. The response rate was only 45.8%, so conclusions must be guarded. However, in the responding population one in three women experienced subsequent moderate-to-severe pelvic floor dysfunction and this risk was increased following the use of vacuum extraction. Interestingly, Caesarean section did not significantly decrease the risk when compared to expectant management. As the unpredictable nature of childbirth poses challenges, we may need to wait for advancements in artificial intelligence, machine learning and complex algorithms to tell us when and how to deliver pregnant individuals.