The Best Start - caesarean section rates: review report

Reasons for caesarean section rates

Critical analysis of the available literature and evidence on the reasons for caesarean section.

Caesarean sections rates have steadily increased throughout the world over the last three decades. The rates of caesarean section vary considerably internationally. According to data from 150 countries, the proportion of births by caesarean section ranges from 6% to 56%.^[70] In 1985, the WHO stated that the optimal caesarean section rate for a country was 10-15%.^[71]

Although some ecological studies have suggested that socioeconomic factors may influence the variance in both caesarean section rates and maternal and infant mortality rates to an extent,^[72] there is currently no standardised internationally accepted classification system to monitor and meaningfully compare caesarean section rates across different countries, facilities, cities or regions in an effective way to understand what factors are influencing this variance.

In 2011, the WHO conducted a systematic review of available systems to classify the use of caesarean section and concluded that the Robson classification is the most suitable to fulfil international and local needs.^[73] The system classifies women into 10 groups based on their obstetric characteristics (parity, previous caesarean section, gestational age, onset of labour, fetal presentation and the number of fetuses). This classification is simple, prospective, clinically relevant and is based on basic obstetric characteristics that are routinely collected – meaning all women can be immediately classified upon being admitted for delivery.^[74]

In literature on clinicians' views on mode of birth, the most cited clinical factors which influence clinicians' decision to perform a caesarean section were maternal BMI above 35, advanced maternal age and previous caesarean section.^[75],[76]Observational studies have shown that there is a higher incidence of intrapartum complications among women with obesity compared to women with a healthy weight. There is also an increased risk of slow labour progression, shoulder dystocia and emergency caesarean section within this group.^[77],[78]

Over four decades, the global rate of obesity has doubled to become one of the largest global public health challenges. Several studies have reported that maternal obesity is associated with an increased risk of a number of serious adverse outcomes, including miscarriage, birth defects, thromboembolism, gestational diabetes, pre-eclampsia, dysfunctional labour, postpartum haemorrhage, wound infections, stillbirth and neonatal death^[79].

A combination of higher maternal age, rising caesarean rates and increasing levels of obesity and chronic disease, such as diabetes, mean that more pregnancies are medically complex.^[80] Increasing maternal age and deprivation are both known to be risk factors for a higher maternal BMI. Increased maternal age is associated with a range of risks and adverse outcomes including placental abruption, placenta praevia, malpresentation, low birthweight, preterm and post–term delivery, and postpartum haemorrhage and still birth.^[81] Due to these risks induction of labour is widely practiced as an intervention to reduce these risks. Talaulikar and Arulkumaran (2011) suggest that high rates of induction, coupled with emerging evidence that upward of 20% of these inductions of labour fail, contribute to increasing rates of caesarean section. WHO guidance (2011) advises, however, that failed induction of labour does not necessarily indicate caesarean section.

Some of the literature suggests that a prevalent indication for primary caesarean section is 'non-progressive labour' or failure to progress in labour, despite lack of association between relatively prolonged labour without indications of foetal distress and detrimental health outcomes.^[82],[83] The acceptable time for labour to progress has grown progressively shorter over recent decades without any clear medical indication of why. ^[84] Arrest of labour 'disorders' are a common indication of primary caesarean section and some health professionals may have an overly narrow view of what healthy labour progression constitutes.^[85]

The views of obstetricians and midwives, and the role they play in influencing decision making around caesarean sections is important in helping to understand the variance in caesarean section rates. Studies which aim to offer insight into obstetricians' and midwives' views on caesarean sections and the factors that influence the decision mainly focus on clinicians' personal beliefs, perceptions of risk and safety and clinician characteristics.^[86] A study of Australian obstetricians and midwives found that elective caesarean section was often perceived as a 'safe' option by obstetricians.^[87]

The perception of risk of mode of birth was subjective among obstetricians and midwives, depending on their personal and medical experience. Clinicians' confidence and skill in communicating risk is an important factor in women's decision making on mode of birth; regarding supporting women considering vaginal birth after caesarean section (VBAC) midwives in an Australian study believed that a woman's decision on mode of birth was often dependant on the doctor they get and how the information is given to them.^[88] Several studies have attempted to understand clinicians' views on caesarean section by maternal request. When questioned on women's rights to request a caesarean section and their willingness to agree to perform one, over half of the obstetricians in a US study (54.6%),^[89] and over one-third in studies in Turkey (40.8%)^[90] and Denmark (37.6%)^[91] believed women should have the right to choose and would agree to perform a caesarean section following discussion of the risks and consequences.

In 2015 the Montgomery v Lanarkshire case drew fresh attention to the communication of risk and informed consent in the UK. The Montgomery ruling makes it clear that any intervention must be based on a shared decision-making process. To deliver the shared-decision making process mandated by the ruling, women and their healthcare provider should both have access to the same standardised information at all points in the care pathway. This means healthcare providers should take time to clearly explain the risks and benefits of a recommended course of action and the alternatives available. Women should be given the time to reflect on the information they are given before deciding what is best for them.^[92]

The Royal College of Obstetricians and Gynaecologists acknowledged in 2016 that obstetrics deals with a unique set of circumstances concerning two individuals, both the mother and baby, where the course of action and urgency of care can change quickly and dramatically, and obstetrics also covers both elective and emergency scenarios and will require a different approach.^[93]

Evidence also suggests that once practice has become embedded it is difficult to dislodge. A qualitative study of midwives' views looked as the routine use of study of intrapartum electronic fetal monitoring (EFM), which has resulted in an increase of operative and instrumental deliveries. The study of two NHS trusts in north England found that midwives' routinely used EFM, regardless of clinical need in an attempt to manage the psychological burden of the threat from clinical negligence. The midwives interviewed lacked confidence in the ability of EFM to accurately detect fetal compromise but were aware that the visual monitoring record is recognised as a valuable piece of legal evidence.^[94] The embedded use of EFM, fear of clinical negligence and the Montgomery ruling may all play a role in the current rate of caesarean sections in the UK. Lack of training, skills or experience have been highlighted as barriers to change among healthcare professionals.^[95]