The second stage of labour is defined as full cervical dilation until delivery of the baby. In fact, it is so much more. The woman embodies both physical strength and emotional vulnerability as with each push she journeys closer to the life changing rite of passage that is motherhood. Labour has long been conceptualised into stages with measurements and time limits. In 1954, EA Friedman devised the partograph, enabling women's labours to be managed with time constraints and boundaries. Despite a Cochrane review (Lavender et al, 2013) concluding that the use of the partograph was not recommended, this approach continues to underpin midwifery practice, potentially resulting in superfluous physical and emotional suffering for women undergoing interventions to shorten their labour.
Aim
This literature review sought to investigate whether low risk mothers and babies suffered adverse effects when the second stage of labour was extended beyond ‘normal’ time limits. These limits are defined by the National Institute for Health and Care Excellence (NICE) (2014) as 3 hours in primiparous women and 2 hours in multiparous women; however, the Royal College of Obstetricians and Gynaecologists (RCOG) (2011) and Trust guidelines provide conflicting advice, meaning that it can be difficult to gain consistency and promote normality.
Methods
Several databases (CINAHL, Medline and Maternity and Infant Care) were comprehensively searched with limiters set so that only the most recent peer reviewed research was generated. Randomised control trials were favoured. The studies were then analysed using a Critical Appraisal Skills Programme (CASP) tool until four studies remained. These studies were then critiqued for their strengths and weaknesses.
Literature review
Study one: Gimovsky and Berghella (2016)
The aim of Gimovsky and Berghella's (2016) study was to evaluate whether extending the length of second stage in primiparous women affected maternal and neonatal outcomes. The study was a randomised controlled trial, which is deemed to be superlative as cause and effect between intervention and result is easy to establish (NICE, 2017). The participants were randomly assigned by computer to either the usual care group, which was to expedite delivery after a 3 hour second stage for women with an epidural, or the extended care group, which allowed women an extra hour to birth their baby. Of the 41 women in the extended group, 21 had a spontaneous vaginal delivery (SVD), compared to just seven of the 37 women in the usual group. A x2-test found that this statistic holds a relative risk of 2.71 (95% confidence interval (CI); P=0.05), which was considered statistically significant. Caesarean section rates were halved and there were no significant differences in adverse maternal and perinatal morbidity.
Strengths of this study included the clear inclusion and exclusion criteria, the fact that all women pushed via the Valsalva technique and that there was no loss to follow up. All participants were similar in age, ethnicity and body mass index (BMI) at the beginning of the trial, with the authors detailing the women's personal characteristics to allow readers to judge how applicable the results were to other populations. Furthermore, the research was peer reviewed, thus increasing its validity and reliability.
Although 946 women were recruited to take part, only 78 met eligibility criteria and consented, which the authors themselves admitted may have rendered the study underpowered to detect small, but potentially clinically important, differences. However, underpowered trials are still beneficial: some information is better than none and the results can be combined in a meta-analysis or systematic review.
Another point of note is that the CI for incidence of third and fourth degree tears was wide (0.68–42.90), possibly indicating unreliability. Further investigation with a larger sample size was recommended.
All participants had epidurals, which was beneficial as it meant that another variable was controlled. However, it was also unfavourable because the findings may not be applicable to women without epidurals, as only 16.4% of women have this type of analgesia in labour (Health and Social Care Information Centre, 2015). A Cochrane review (Anim-Somuah et al, 2011) found that epidurals increased the duration of the second stage and the chance of instrumental delivery, meaning that the participants may have had fewer assisted vaginal deliveries (AVD), had they not had epidurals.
Blinding is a crucial safeguard against bias, but due to the nature of the variables being tested, this was not possible, which meant that participants and health professionals may have acted differently from normal and thus swayed the results.
There was also a 14.1% crossover rate for ethical reasons that meant that the interventions had to be discontinued for these women. Their outcomes were still analysed, however, despite not taking part.
‘It was found that rates of chorioamnionitis increased by 7.1% in primiparous women and quintupled in multiparous women following prolonged labour, although high rates cannot necessarily be attributed to extended labour‘
Study two: Laughon et al (2014)
This study of 103 415 women set out to assess maternal and neonatal outcomes following a prolonged second stage of labour. Medical data were obtained electronically from 19 hospitals for women who had single vertex presentations at 36 weeks gestation or more and who had reached 10 cm dilated. Prolonged second stage was defined as: 3 hours or more in primiparous women with an epidural and 2 hours without; or 2 hours or more for multiparous women with an epidural and 1 hour without. It was found that rates of chorioamnionitis increased by 7.1% in primiparous women and quintupled in multiparous women following prolonged labour. However, it is important to note that high rates of chorioamnionitis cannot necessarily be attributed to extended labour, as there can be many other causes, such as prolonged rupture of membranes and Group B streptococcus.
Incidence of third and fourth degree tears slightly increased in women with extended second stage labour. However, risk of third and fourth degree tears significantly increases with AVD, meaning that the rise in incidence in this study could be due to the increase in AVD and not prolonged labour. Besides this, there were no differences in maternal and perinatal outcomes for women experiencing longer labours.
Overall, extended second stage labour was associated with highly successful rates of vaginal delivery and decreased caesarean section, which is advantageous given the multitude of potential complications associated with caesareans. Interestingly, the overriding reason for caesarean section following prolonged labour was not fetal distress but cephalopelvic disproportion, indicating that these women would not have achieved a SVD regardless of length of second stage.
The study detailed the personal characteristics of the primiparous women but offered no information about the multiparous women, making it unclear whether the groups were similar or if there were other factors contributing to their prolonged labours and morbidities such as previous third degree tear, which has been proved to increase a woman's risk of suffering another in a subsequent delivery.
A major strength of this study was the large sample size and rich patient-level data from multiple institutions, although this could mean some of the results are false positives, given the large number of comparisons. Another strength of Laughon et al's (2014) study is the fact that it was retrospective. This meant that the women and health professionals did not know that they were going to be analysed, therefore bias that would have come from them acting differently was eliminated. This did nevertheless mean that extraneous variables, such as pushing technique, were not controlled. Retrospective trials are limited to the data available in the records but there may have been other variables relevant to the study, such as maternal positioning and pushing technique, which were not captured.
‘The issue of extending time limits in the second stage of labour for low risk women is controversial, as research suggests there are both advantages and disadvantages to doing so‘
Study three: Yli et al (2011)
Yli et al (2011) observed a population of 22 812 Swedish women to assess the effect that duration of pushing had on perinatal outcomes. The women, both primiparous and multiparous, carried singleton cephalic pregnancies at 36 weeks gestation or more. The research demonstrated that chance of SVD decreased with each 30 minutes of pushing extra and therefore the likelihood of AVD increased. There were also higher frequencies of babies being born with a cord pH of less than 7, although this could have been due to the high risk conditions from which the women suffered. The odds ratio for a 5-minute Apgar score of less than 7 doubled after 60 minutes of pushing, although the authors noted that this may be due to maternal drugs, meconium aspiration or congenital defects. This study accepted a wider inclusion criteria than the other trials, allowing high risk mothers and babies to take part even though their outcomes could be ascribed to their medial conditions rather than duration of second stage.
A strength of this research is the large sample size, as results are more likely to be reliable and clinically useful.
A limitation of Yli et al's (2011) study is the use of a highly academic tone and convoluted language, making it difficult to interpret and extract key information. Furthermore, the study assessed only perinatal outcomes, and ignored the maternal. This is because assessing methods of electronic fetal monitoring, as opposed to duration of pushing, was the main outcome for all three studies that Yli et al included in their research. Although the studies recorded length of active pushing, this may not have been recorded accurately, as other variables were the main focus.
There was no information specifying pushing techniques or whether the women had some passive time once fully dilated to allow for descent. Furthermore, some of the trials included in the study were missing crucial information such as maternal age, epidural status and induction rates—all of which can have an impact on second stage duration and perinatal outcome.
Study four: Rouse et al (2009)
The purpose of Rouse et al's (2009) secondary analysis of an American randomised controlled trial was to assess maternal and neonatal outcomes in relation to second stage duration. Of the 5341 participants, 4126 reached the second stage. Maternal and perinatal data was collected by trained research nurses who were present during the labour. The duration of second stage was calculated as time elapsed from the first vaginal examination that confirmed full dilatation, until birth. This was interesting, as a woman can be fully dilated for some time before the midwife confirms with a vaginal examination and, once the decision has been made to expedite delivery with obstetrical assistance, waiting for the anaesthetist or a theatre to become available can often cause a delay.
Rouse et al (2009) found that the 3-4 hour mark was the point at which SVD, AVD and caesarean section rates were all the same, each representing roughly a third of delivery methods. As time increased, SVD rates gradually declined and the numbers of AVDs and caesarean sections increased, although the reasons were predominantly for cephalopelvic dystocia rather than fetal distress. This finding is concurrent with Laughon et al's (2014) study, which, in addition to the fact that Rouse et al (2009) did not detect any adverse neonatal outcomes, emphasises the fact that extended second stage does not necessarily place the baby at risk.
Third and fourth degree perineal lacerations and chorioamnionitis rates peaked at 3–4 hours and decreased thereafter. This could have been due to AVD carrying a greater risk of perineal trauma, as does nulliparity, which applied to all the women in this study. The woman's birth position can also account for occurrence of third and fourth degree perineal trauma rates, as it is known that upright positions, such as sitting or squatting on a birthing stool, increase a woman's chance of suffering worse degrees of perineal injury.
Uterine atony rates increased by 5.7% from a second stage lasting less than an hour to one lasting over 5 hours. However, there were other factors that could influence risk of an atonic uterus, such as parity, duration of first stage, management of third stage and third stage drugs, details of which were not included in the study.
A strength of this research is that all the participants were nulliparous, as opposed to some of the studies discussed in this literature review, which included both primiparous women and multiparous women and did not differentiate between outcomes.
A limitation of this data is that labour management was not standardised, which somewhat limited the value of the causal implications of the data. This study held a wider inclusion criteria than others by accepting high-risk women onto the trial with little or no detail about why they were high risk, meaning that complications observed in association with second stage duration might not be due to duration alone. For example, babies with abnormalities were not excluded from the study and may have had to visit special care regardless of second stage duration. This means that this outcome could not have been prevented had second stage been terminated earlier.
No research on the lasting effects of prolonged second stage, such as uterine prolapse or haemorrhoids, could be found, suggesting that this is an area that requires further investigation to aid women in their decision-making and to allow them to make fully informed choices regarding their labour management.
Conclusions
Overall, the research proposes that as second stage increases, the chance of achieving a SVD does too. However, some studies included in this review have shown that morbidities, such as chorioamnionitis, severe perineal trauma and poor neonatal outcome, may also slightly increase, although no studies reported increased likelihood of postpartum haemorrhage. The slightly increased risk of morbidity must be weighed up against the potential risks associated with AVD and caesareans, which include pelvic floor and organ damage, infection, neonatal injury, and increased blood loss.
The issue of extending time limits in the second stage of labour for low risk women is controversial, as research suggests there are both advantages and disadvantages to doing so. This literature review found some evidence to suggest that there was some degree of neonatal deterioration with prolonged pushing.
In view of this, health professionals should view guidelines as recommendations rather than rules and consider the wider picture, which is the clinical wellness of mother and baby and, importantly, the woman's own wishes. All too often, women unwillingly consent to procedures that they later regret, as a result of not being fully informed about their choices. It is in the midwives' Code (Nursing and Midwifery Council, 2015) to empower people by involving them in decisions about their care and to respect individual choice to refuse treatment. It is the midwife's role to advocate for women and work in partnership with the multidisciplinary team in order to achieve optimal outcome for both mother and baby. Women are not victims of their circumstances; they are powerful driving forces that can carve their own paths by taking ownership of their life and decisions.
However, there is no reason why women and health professionals cannot work in partnership to evaluate the risks and benefits to achieve the safest outcome with the fewest detrimental effects.