The author has been following, with interest, the debates and discussions around the trend of increasing induction rates across the UK, influenced in part by the drive to reduce stillbirth, neonatal mortality and brain injury by 2025. This trend has been formally recognised by a variety of sources, including progress reviews of ‘Better births’, the second version of ‘Saving babies lives care bundle’ (SBLCB) and the National Maternity and Perinatal Audit (NHS England, 2019; National Maternity and Perinatal Audit, 2019; Maternity Transformation Programme, 2020). Current data indicates that while the most common labour onset mode remains spontaneous (albeit less than half at 49 % in 2019–2020), this has decreased from 68% in the years 2009–2010. A corresponding rise in induction rates from 21%–33% in these years has been observed with an associated steady decline in stillbirth rates since 2013 (Draper et al, 2020; NHS Digital, 2020).
The authors of the current iteration of the SBLCB recognise that a consequence of pathway introduction is often an associated ‘intervention creep’, a contributory factor in the corresponding rise in induction rates (NHS England, 2019). Spillane (2020) succinctly addresses this congruence between the rise in induction rates and corresponding reduction in stillbirth rates but, crucially, acknowledges the complexity of multifactorial influences which lead to stillbirth cannot be negated through early induction alone. Undeniably, it follows that while induction of labour remains an important intervention in reducing mortality, it must be undertaken in the presence of individualised risk assessment and with fully informed, shared decision-making, ensuring there is scope for evaluation of and reduction in obstetric intervention (NHS England, 2019; Spillane, 2020).
It is against this background that some NHS trusts in the UK have started routinely offering membrane sweeps to women and pregnant people as early as 38 weeks in an effort to reduce the number of inductions of labour at term with anecdotally reported success in reducing rates. This development is problematic given the lack of evidence and guidance that supports the provision of membrane sweeping at this gestation to reduce the likelihood of formal induction of labour (National Institute for Health and Care Excellence [NICE], 2008). It is unclear regarding the criteria for this being offered (parity, risk status etc), whether there is commonality of implementation across trusts and whether those who have implemented this policy have gathered data to evaluate the intervention. What is apparent, however, is that a cursory search on social media and popular parenting websites quickly uncover narratives of women and birthing people having upwards of 10 membrane sweeps before labour begins which contribute to feelings of disappointment, exhaustion and a distrust in their own bodies' ability, even before being offered a formal induction.
Current UK guidance suggests that a discussion at or around 38 weeks should be held to advise women and pregnant people that most will spontaneously labour before 42 weeks and that clear information be provided of the risks of pregnancy past this gestation, as well as the risks and benefits of membrane sweeping. This includes, but is not limited to, the likelihood of membrane sweeping increasing the chance of spontaneous onset labour, a corresponding reduction in the likelihood of induction, advice around what is involved when performing a membrane sweep, and that discomfort and vaginal bleeding is a possible outcome. A vaginal examination for membrane sweeping should then be offered to women and birthing people who have not birthed by 41 weeks (40 weeks if nulliparous) (NICE, 2008a; 2008b).
Interestingly, the current NICE guidelines suggest that membrane sweeping is not considered a method of induction but an adjunct; however, the scoping document for expected review of this guideline in 2021 suggest that the review will include ‘the effectiveness of methods for induction … including membrane sweeping…’ (NICE, 2019). Semantic maybe, however it must be made clear whether membrane sweeping is to be considered an adjunct or indeed be considered a more formal method of induction within the review, particularly if there is a move to offer repeated membrane sweeps at less than 40 weeks' gestation and the potential implications. Upon what evidence is membrane sweeping at 38 weeks based? This is certainly not a new issue and was discussed previously by Wickham (2011), highlighting that a Cochrane Review in the subject concluded that ‘…the rationale for performing routinely an intervention with the potential to induce labour in women with an uneventful pregnancy at 38 weeks of gestation is, at least, questionable … the reduction in the use of more formal methods of induction needs to be balanced against women's discomfort and other adverse effects' (Boulvain et al, 2005).
A recent update to the Cochrane Review explored the effects and safety of membrane sweeping in women at or near term (Finucane et al, 2020) and included 44 studies with gestations ranging from 36–42 weeks. The findings suggest that overall membrane sweeping may be effective in encouraging spontaneous onset of labour (598/1 000 vs 723/1 000) and reducing the likelihood of induction of labour (313/1 000 vs 228/1 000), acknowledging that the differences were small and the certainty of the reviewed evidence was low (Finucane et al, 2020).
The authors found no difference between groups for outcome including maternal or neonatal morbidity and mortality, caesarean section or instrumental vaginal birth. Importantly, no conclusions could be drawn in terms of ideal timing for membrane sweeping as none of the included studies observed the consequences of performing a membrane sweep at differing gestations, indeed the authors recognise that more evidence is needed to evaluate the ideal gestation at which membrane sweep should be offered and the ‘impact gestation may have on the success of membrane sweeping’ as well as frequency of performance (Finucane et al, 2020).
It is worth considering that alongside the likelihood of spontaneous labour and avoidance of induction, there exists known risks of membrane sweeping, including vaginal bleeding, discomfort during and after the procedure and the onset of irregular or regular contractions. However, less often discussed with women and birthing people includes the number of membrane sweeps needed to be undertaken to avoid a single induction of labour is (NNT=7) (Boulvain et al, 2005) and while there is little evidence that an increase in infection rates exist, a recent study conducted by Avdiyovski et al (2019) suggests an increased risk of pre-labour rupture of membranes, crucial when considering performance of membrane sweeping at 38 weeks.
The emotional and social implications for the woman or birthing person who is exposed to potentially numerous membrane sweeps from any gestation but particularly from 38 weeks could, as previously discussed, have a considerably detrimental emotional and physiological effect (Wickham, 2020). If, as is suggested, membrane sweeping increases the likelihood of spontaneous onset of labour and avoidance of induction by accelerating and promoting the physiological processes of labour and parturition, then it also follows that another possible implication of continued and repeated unnecessary membrane sweeps in the absence of a clinical indication before the recommended 40 or 41 weeks, is the potential for adverse effect and iatrogenic harm related to physiological, psychological, hormonal and emotional processes of labour.
An important inclusion within the Finucane et al (2020) review was the inclusion of maternal satisfaction of the intervention. The majority of women and birthing people revealed a positive experience with membrane sweeping, suggesting that when balancing advantage against disadvantage, they would on the whole recommend the intervention or choose it again in future pregnancies. It is important to note, however, that these data were drawn from the only three studies out of 44 that explored maternal satisfaction alone and that possible bias may have been present in these data. To this end, Boulvain et al (2005) suggest that there remains insufficient evidence from which to draw meaningful inferences.
A synthesis of qualitative literature by Roberts et al (2020) explored information needs, decision-making and experiences of membrane sweeping to promote spontaneous labour. The authors discovered a general lack of subject-specific, qualitative evidence in relation to information needs, decision-making and experiences of the intervention, troubling viewed through the lens of rising induction across the UK. Further examination of related literature provided a valuable illustration of the need for accurate, adequate and targeted information around the whole induction process as well as shared decision-making, absent of coercive practise (Roberts et al, 2020). Equally troubling was the reported case of membrane sweeping without informed consent as part of a vaginal examination (Stevens and Miller, 2012). Roberts et al (2020) urge caution in drawing conclusions from an isolated case; however, it does make for uncomfortable reading, as membrane sweeps being undertaken without consent during a vaginal examination prior to the procedure or without full discussion of risk and benefit could result in serious professional ramifications as well as detrimental implications for that pregnant individual.
The author is not suggesting that there is no scope for a discussion to be opened, quite the contrary in fact, and would urge any trust where this is being offered to share their outcomes in order to inform future research and service improvement. It is also crucial that women and birthing people experiences of this intervention are explored in order to strive to work within best evidence, including the provision of clear and honest information to aid decision-making.
Ultimately, when considering blanket implementation of what is likely be assumed a low-risk intervention before 40 weeks, there must be reflection upon the true implications of the practise as well as consideration of for whose benefit this intervention is being offered. Such consideration should include whether the full physical and psychological risks and benefits are being fully discussed, including the absence of evidence to support early membrane sweeping because, as Wickham (2020) eloquently suggests, ‘stretching and sweeping isn't benign’.