The benefits and safety of vaginal birth after primary caesarean section (VBAC) is a subject of considerable interest to midwives, and one which this journal periodically revisits. Some of this discussion is informed by contrasting views about childbirth. One influential standpoint sees birth as a risky biomedical process, and medical interventions should be used to lessen any risks. A contrasting outlook considers birth, while having elements of uncertainty, to be a normal and life-affirming event for women. This opinion is shared by many midwives (Downe and McCourt, 2008) and is endorsed by professional bodies such as the Royal College of Midwives (RCM, 2016) in its Better Births Initiative. Balancing these opposing perspectives about childbirth in everyday practice is a formidable task. This article examines prevailing ideas about the safety and benefits of VBAC, highlighting the effects of previous caesarean and other influences on women's choices in subsequent pregnancies.
Reasons for initial caesarean
Annually, there are nearly 23 million caesarean births worldwide (Molina et al, 2015). High rates of caesarean birth are concerning as this situation is not considered to be in women's best interests (Hyde et al, 2012; Spong et al, 2012). Some conclude that continued increases in rates of caesarean are economically unsustainable, owing to the extra financial costs of caesarean birth compared with vaginal birth (Fawsitt et al, 2013). Cragin's historic quotation ‘once a caesarean, always a caesarean’ (Cragin, 1916: 3) has become a popularised axiom about women's birth mode choices after primary caesarean. Despite its age, the quote continues to be used in professional literature by both proponents and critics of VBAC e.g. Bangal et al (2013) and Micek et al (2014). The phrase also remains influential in internet information sources and social media discourse around VBAC that is targeted at pregnant women. Because of its ubiquity, Cragin's statement warrants closer scrutiny. Interestingly, the original text was prefixed, ‘the usual rule is…’ and followed by, ‘many exceptions occur’ (Cragin, 1916: 3), suggesting a more uncertain view. Craigin recalled one woman having three vaginal births without incident after uterine surgery (i.e. VBAC). Reading this additional detail suggests that Cragin held a less polemic opinion about the likelihood of repeat caesarean than he is sometimes credited with by those quoting him.
Undeniably, some caesareans are necessary; however, there is concern about overuse of the intervention (Lavender et al, 2012; Caughey et al, 2014). International consensus about optimal caesarean rates is lacking (Macfarlane et al, 2016; Betrán et al, 2016). In part, this is because optimal rates may vary depending on population characteristics and be influenced by models of maternity care. Molina et al (2015), using birth data from World Health Organization (WHO) member states (n = 194, collected during 2005–2012), found that the relationship between caesarean rates and mortality was inconsistent. They concluded that rates above 19% were not associated with further declines in mortality. Ye et al (2014), modelling 30 years of WHO birth data from 19 countries, found that caesarean rates above 10% did not improve maternal or neonatal survival. In view of this research, the WHO (2015) has refined its recommendation about optimal caesarean rates and now advocates that rates should not exceed 10% of live births. However, many developed nations far exceed this figure (Caughey et al, 2014). Current data for England suggest that around 22.1% of primiparous births are caesareans, though this figure masks considerable inter-hospital variation (Carroll et al, 2016). In part, this is because elective repeat caesarean section (ERCS) owing to a low rate of VBAC affects overall rates (Mone et al, 2014; Schemann et al, 2015).
Medical indications for caesarean are relative or absolute. Events such as cord prolapse and placenta praevia, for example, are unconditional and caesarean birth can be lifesaving (Ye et al, 2016). However, many indications for the procedure are open to differing interpretation by clinicians. This situation might be instrumental in the variations in rates seen between hospitals (Lavender et al, 2012). Brennan et al's (2009) analysis of data from the UK and USA found that women of higher social status were more likely to request a caesarean birth. Popular media provides extensive, often derogatory, coverage of this so-called ‘too posh to push’ trend (McGrath and Ray-Barruel, 2009). Karlström et al's (2011) study (n = 1506) challenges this prejudice; they found that only 7.0% of women in late pregnancy expressed a preference for caesarean. Many of these women who wanted a caesarean birth reported troublesome past experiences and fear of childbirth as motivating factors, a finding replicated in other studies (Faisal et al, 2014; Black et al, 2016). Relieving childbirth-related fear will help to ensure women make informed and supported choices, rather than ones based on emotion alone; this is an important element of a midwife's role and may have an impact on requests for caesarean birth. Whatever the explanations for the rise in caesarean births, they are complex and multifactorial.
Caesarean birth and its risks
Historically, caesarean birth had high mortality (Cragin, 1916). Birth is a safer and less risky endeavour today, regardless of mode of delivery. Nevertheless, compared with vaginal birth, surgical birth has greater mortality. However, precise figures for the UK are difficult to interpret. In part, this is because of a difference in definitions, clinical practice and how data are collected throughout the UK (Macfarlane et al, 2016). As such, statistics concerning differential mortalities between vaginal and caesarean birth should be viewed cautiously to avoid erroneous conclusions. Caesarean birth has acute and longer-term morbidities including: wound infections, excessive blood loss, injury to internal organs, increased hospital stay, negative emotions, lower Apgar scores, and more infant respiratory problems (Hyde et al, 2012; Lavender et al, 2012; Molina et al, 2015). In addition, subsequent pregnancies carry higher risks of placental abnormalities and uterine rupture (Gurol-Urganci et al, 2011; Fitzpatrick et al, 2012).
For infants, new evidence is emerging around lifelong consequences of caesarean birth including, for example, immunological effects (Sevelsted et al, 2015). An intriguing notion gaining credence is that labour is a critical physiological life event which has influential epigenetic effects (environmental effects affect ing gene expression) (Hyde et al, 2012; Dahlen et al, 2013). Epigenetics could explain the mech anism through which the health effects of caesarean birth operate. However, more investigation is required as the evidence is mixed and subject to confounding variables (Dahlen et al, 2013). These possibilities support the view that practitioners should promote vaginal birth to women as the preferred option unless it is clinically contraindicated.
Vaginal birth after caesarean
VBAC is associated with health gains for women, helps them avoid repeated surgery and could have important health benefits for infants. Debates surrounding VBAC are often framed around concerns about the risks of uterine rupture and avoiding the higher rates of complication associated with repeated caesarean (Mone et al, 2015). Uterine rupture has significant morbidities, though its incidence varies geographically and temporally (Royal College of Obstetricians and Gynaecologists (RCOG), 2015). This situation reflects differences in: data quality, definitions, sociodemographics, clinical practices, and the availability of maternal care (Jastrow et al, 2010).
Though potentially life-changing, uterine rupture in the UK is rare; figures of around 0.5% are widely quoted (RCOG, 2015). Fitzpatrick et al (2012) determined the rate to be 0.02%, rising to 0.21% for planned VBAC. Expressed another way, these figures suggest that the risk of uterine rupture during attempted VBAC is around 1 in 200 (RCOG, 2015) to 1 in 480 (Fitzpatrick et al, 2012). The message from research is that VBAC carries minimal additional risk and should normally be offered to most women (Dodd et al, 2013)—a view endorsed by professional guidance (RCOG, 2015).
Increasing rates of primary caesarean have led to more women having a history of prior caesarean in second pregnancies. Successful VBAC has the potential to help reverse the upward trend in caesarean birth rates (Carroll et al, 2016). International comparisons suggest VBAC rates vary between countries (Table 1). Further analysis of these headline figures reveals significant variation within countries. For example, Knight et al (2014), in a study of second births in England after previous caesarean (n = 143 970), found that over half (52.2%) of women attempted VBAC. In comparison, Carroll et al (2016) report VBAC rates between 11.9% to 44.2% in English hospitals. It may be argued that these variations reflect differences in relative risks between populations served by particular hospitals. However, in the Carroll et al (2016) study, the raw data were adjusted for maternal characteristics, which ensures the data are directly comparable. It is unclear what factors influence this variation, but the organisation of services, place of birth, prevailing childbirth models, national guidance and women's own preferences are influential on women's decisions concerning VBAC (Rimkoute and South, 2013; Knight et al, 2014; Tolmacheva, 2015; Black et al, 2016). This leaves an unanswered question: why don't more women choose to attempt VBAC?
Table 1. International comparisons: rates of vaginal birth after caesarean in selected developed nations
| Country | Vaginal birth after caesarean attempt rate |
|---|---|
| Sweden | 55.0% |
| Finland | 45.0% |
| UK | 27.8% |
| Spain | 20.0% |
| Australia | 12.3% |
| USA | 10.6% |
| Latvia | 9.0% |
Predicting VBAC success
Figures about the likelihood of successful planned VBAC suggest that around 63.4% (Knight et al, 2014) to 72–75% (RCOG, 2015) of attempts will be successful; this can increase to around 85–90% for women who have had a previous vaginal birth (RCOG, 2015). Studies have reported on demographic and clinical characteristics associated with successful and unsuccessful VBAC (Table 2; Table 3) and combinations of these have been used to design predictive models. Mone et al (2015) sought to evaluate and statistically validate three different models for a UK population that might predict VBAC success. The models that more accurately predicted outcome included more maternal characteristics and were developed using populations similar to those in the study. This suggests there is a need for specific population-based validation of these instruments. Prediction tools have the potential to offer guidance to obstetricians and midwives when they counsel women about birth options. Such tools could also support shared decision-making (Shafir and Rosenthal, 2012; Horey et al, 2013: Schoorel et al, 2014) and reduce decisional conflict (Dugas et al, 2012; Cox, 2014).
Table 2. Characteristics predicting successful vaginal birth after caesarean
| Maternal age less than 30 years |
| Body mass index less than 30 kg/m2 |
| White ethnicity |
| Psychologically letting go of previous negative birth experience |
| Previous caesarean was non-emergency |
| Spontaneous onset of labour |
| Previous vaginal delivery or VBAC |
| Lower segment uterine incision |
| More than 12 months since prior caesarean |
| Absence of medical indications for caesarean delivery |
Table 3. Characteristics predicting less successful vaginal birth after caesarean
| Maternal height below average stature |
| Male fetus |
| Birth time beyond term |
| Induction of labour |
| No previous vaginal delivery |
| Fetal heart rate abnormalities |
| J-shaped uterine incision |
| Less than 12 months since prior caesarean |
| Primary caesarean was emergency |
| Fetal macrosomia |
| High maternal body mass index |
| Non-white ethnicity |
For a woman to make informed choices regarding VBAC, she needs to know her personal risks associated with VBAC compared with repeat caesarean (Cook et al, 2013) and how these interact with her personal beliefs and desires around childbirth. Partly to respond to this need and support women's agency, several instruments have been developed for women to use themselves (Shorten et al, 2015); for example, the Maternal-Fetal Medicine Units VBAC calculator (available at http://tinyurl.com/nubfqvm) (Grobman et al, 2007). These forecasts are limited in their utility, as they are based on population analyses and a woman's clinical risk is dynamic, reflecting changes in her body during pregnancy. In view of these features, it might be potentially useful to delay final decision about VBAC or ERCS until pregnancy is more advanced (Lundgren et al, 2015). This would allow time for women to consider their choices and for potential risks to emerge, and may contribute to strategies to increase VBAC rates.
Why women make the choices they make
Current evidence-based guidance (RCOG, 2015) states unequivocally that VBAC is a safe choice for most women, with few contraindications. It is unclear why some women make the choices they make, but clearly there are many factors, both intrinsic and extrinsic. There is a need to understand what influences women to make particular decisions about their mode of delivery following caesarean birth. Doing this could help to inform initiatives to support women to decide on VBAC and receive support to make the attempt successful.
Birth is a very personal time for women and, for some, fears about childbirth are pervasive and influence their decisions (Faisal et al, 2014). To help gain insight into factors influencing women's decisions around VBAC, one review of studies published between 2000 and 2014 (n = 9) identified several prominent factors (Tolmacheva, 2015). The author's synthesis was organised into themes and encompassed a need for women to maintain control, make choices that reflected their personal philosophies surrounding birth, and accommodate their previous birth experience. Everyday practical considerations, such as recovery time post-birth and clinicians' influences, also featured. A recurring theme in several studies examining factors influencing women's decisions about VBAC is the central importance of how maternity care is organised and how midwives and obstetricians interact with women (Lundgren at al, 2012; 2015; Reid and Flannagan, 2012; Gardner et al, 2014; Nilsson et al, 2015a).
There is limited direct evidence about how paternal attitudes affect women's decision-making around VBAC. A study by Johansson et al (2014) identified inherent tensions in men around childbirth. One theme, ‘birth mode is not my decision’, was juxtaposed with a competing narrative that described ‘childbirth as risky’. Some men's preference for caesarean birth has been described in the literature (Hildingsson et al, 2014). In this study, those fathers who expressed this preference also had more fears about childbirth per se. In these studies, caesarean birth was often viewed by fathers as quick, efficient and safe (Hildingsson et al, 2014; Johansson et al, 2014). This suggests that there is a need to alleviate men's fears; addressing these concerns could help them to be more informed and supportive of their partner's decision to attempt VBAC (Robson et al, 2015).
Health professionals are highly influential in how women make birth decisions (Black et al, 2016). For example, Jou et al (2015), in an analysis of US survey data (n = 2400), found a positive predictive relationship between women who reported feeling pressured by clinicians to have a caesarean and them having one. In the UK, Black et al (2016) described how women were guided with encouragement and dissuasion from influential people (such as health professionals, health commentators and social contacts) regarding VBAC and ERCS. Another important influence on women may be how birth statistics are conveyed and explained to them, and how they interpret any figures (Dugas et al, 2012). Studies in health care (Tal and Wansink, 2016) and midwifery (Crawley and Westland, 2016) show that the way in which scientific information is conveyed and the perceived credibility of the information source can be highly persuasive. Midwives and obstetricians play a pivotal role in women's decision-making and must strive to avoid unwittingly biasing the information they convey about the relative risks and benefits of VBAC or ERCS. In addition, when counselling women, midwives must be mindful that they do not convey subtle verbal and nonverbal signals that might suggest a preference for VBAC or ERCS. Failing to address these communication issues may explain why, in some centres, more women elect for ERCS rather than attempting VBAC, though this is speculative and requires research.
Black et al (2016) identified distinctive influences affecting different groups of women who had different birth preferences. Women who chose VBAC were described as confident and driven by long-standing desires to experience a vaginal birth. In contrast, women who elected for ERCS were strongly affected by past negative birth experiences and sometimes guided by other people's opinions about what they should do. Another group, who held no firm convictions, were open to considering the merits of VBAC or ERCS. Emmett et al's (2011) research adds a further confounder, concluding that some women's preferences about birth mode differ between the second and third trimesters. In this study, only 57% of women maintained their preference throughout pregnancy. These findings suggest that it is important to explore women's motivations during antenatal counselling in order to personalise support around their preconceptions. Furthermore, health professionals need to have an understanding of how opinions evolve during pregnancy in order to support women during their birth experience.
The availability of timely, individualised information regarding the benefits and risks associated with particular choices about birth mode could be an important factor in how women decide whether or not to attempt VBAC (Chaillet et al, 2012; Schoorel et al, 2014). This information could be provided during face-to-face consultations, and trustworthy online tools may also have a role to play (Shorten et al, 2015). However, one systematic review (Nilsson et al, 2015b) found that decision aids and concomitant antenatal education had little effect on improving VBAC rates. Nonetheless, such interventions seem to enable women to be more confident in their decisions about birth mode (Dugas et al, 2012; Horey et al, 2013). Providing up-to-date, clear, understandable and balanced information about the benefits and morbidities associated with primary caesarean, repeat caesarean and VBAC is essential (Black et al, 2016). Gardner et al (2014) suggest that this might be best delivered by specialised teams with experience in this aspect of midwifery and obstetric practice, as this can improve VBAC attempt rates. Midwives and service commissioners should pay due regard to this during service reviews.
Women considering VBAC want support from knowledgeable, confident practitioners; in this regard, VBAC is no different from birth in general. However, women planning VBAC seem to desire greater familiarity and confidence in their care providers (Lundgren et al, 2012; 2015). In practice, seeing women who have opted to attempt VBAC arrive at the maternity unit in labour and then deciding to opt out is disheartening—particularly when the reason often given by the woman is that she felt unfamiliar with staff, as the team to which she was accustomed were unavailable, or that she felt unprepared for the experiences of labour. This could be attributable to service limitations or inadequate preparation and counselling beforehand. Addressing these shortcomings would help to dispel the myth that ‘once a caesarean, always a caesarean’.
Conclusions
VBAC is an important element of midwifery practice. Current caesarean rates are unsustainable for many reasons, including: the economic cost of the procedure, the long-term effects on women's reproductive lives and, ecologically, in terms of the possible effects on infants born this way. Therefore, whenever possible, vaginal birth should be promoted as the optimal choice unless contraindicated by explicit medical reasons. Midwifery and obstetric interventions designed to prevent primary caesarean should be recommended to practitioners and mothers.
Many women will enter their second and subsequent pregnancies with a history of prior caesarean; successful VBAC can be beneficial for these women and their children. Women, particularly after primary caesarean, will benefit from being offered tailored support and information during the early postnatal period and then again throughout subsequent pregnancies. Population-based predictive tools can aid collaborative decision-making, but further research should be undertaken to validate them across diverse populations and ensure they meet individual needs. Recent innovative web-based tools designed for women to assess their own risk show promise, and may enable greater self-sufficiency and confidence in decision-making; further evaluation of such tools may enable their routine use. More research is required to adapt and apply the lessons from countries with high VBAC rates and into the utility of interventions designed to support women in making decisions about VBAC or ERCS.
Maternity service managers, midwives and obstetricians need to collaborate with women to ensure their models of care and service structures are optimised to support increased VBAC attempts. This will also ensure that women have sufficient confidence in themselves, their maternity services and health professionals to choose VBAC.
Key Points
- There is a higher rate of long-term morbidities associated with caesarean birth than vaginal birth
- New evidence is emerging that caesarean birth may have important epigenetic effects on infants' long-term health
- Vaginal birth after primary caesarean (VBAC) is a safe option for most women who have had a primary caesarean section and should be routinely offered
- All midwives should continually update themselves with current information and evidence about VBAC, as part of their continuing professional development. This will help to ensure that messages to women are consistent and avoid unnecessary worry and confusion
- Women considering VBAC should be directed towards authoritative sources of information and support throughout the antenatal period so that their questions can be answered and concerns addressed
- Women who choose to attempt VBAC should be supported by specialist and experienced midwives working in multidisciplinary collaboration