Eight studies on my reading list (Summer 2016, part 1)

4553982719_d391550004_nIt’s happened again! My reading pile has got so big that I’ll never catch up if I try to share everything that has caught my eye in individual blog posts, so I’m having a clear out and sharing a bumper crop of juicy-looking studies with you instead … do let me know what you think if you get to read them in full before I do!  The four that I’m sharing today are related to pregnancy, labour, birth and the postnatal period while I’ve got four in the second part of this post that are all linked with breastfeeding 😀


1. Diagnosing onset of labor: a systematic review of definitions in the research literature

There have been some significant leaps in our understanding of how we should best define the onset of labour in recent years, and this paper adds to that debate. It’s important to look at how this is defined differently according to where you go, both in practice and in the research literature. But of even more importance than the findings of various studies and analysis is (in my humble opinion) the need to think deeply about what we do with these: how we change practice and also how we change what we say to women and families. This area isn’t just about when professionals begin to measure; it also relates to key issues about what women do, feel and experience as their labour begins.

Background: The diagnosis of labor onset has been described as one of the most important judgments in maternity care. There is compelling evidence that the duration of both latent and active phase labor are clinically important and require consistent approaches to measurement. In order to measure the duration of labor phases systematically, we need standard definitions of their onset. We reviewed the literature to examine definitions of labor onset and the evidentiary basis provided for these definitions.

Methods: Five electronic databases were searched using predefined search terms. We included English, French and German language studies published between January 1978 and March 2014 defining the onset of latent labor and/or active labor in a population of healthy women with term births. Studies focusing exclusively on induced labor were excluded.

Results: We included 62 studies. Four ‘types’ of labor onset were defined: latent phase, active phase, first stage and unspecified. Labor onset was most commonly defined through the presence of regular painful contractions (71 % of studies) and/or some measure of cervical dilatation (68 % of studies). However, there was considerable discrepancy about what constituted onset of labor even within ‘type’ of labor onset. The majority of studies did not provide evidentiary support for their choice of definition of labor onset.

Conclusions: There is little consensus regarding definitions of labor onset in the research literature. In order to avoid misdiagnosis of the onset of labor and identify departures from normal labor trajectories, a consistent and measurable definition of labor onset for each phase and stage is essential. In choosing standard definitions, the consequences of their use on rates of maternal and fetal morbidity must also be examined.

Hanley GE, Munro S, Greyson D et al (2016). Diagnosing onset of labor: a systematic review of definitions in the research literature. BMC Pregnancy and Childbirth, 16:71 DOI: 10.1186/s12884-016-0857-4


2. Association of the Duration of Active Pushing With Obstetric Outcomes

Let’s stay with labour and birth for one more study. A large observational study of the second stage of labour (though please see here for a useful comment on the notion of dividing labour into artificial stages) challenges current obstetric guidance which seeks to limit the length of time for which women push during labour. The results of this study found that, although a longer duration of pushing was associated with a slightly increased relative risk of problems, the absolute difference in risk was small and more than three quarters of women gave birth vaginally even after pushing for four hours. Given the risks and ramifications of interventions, this is one which I will be looking at more closely.

OBJECTIVE: To estimate the associations between the duration of active pushing during the second stage of labor and maternal and neonatal outcomes.

METHODS: We performed an observational study in which data were obtained by trained abstractors from maternal and neonatal charts of deliveries at 25 hospitals over a 3-year period. In this secondary analysis, women with no prior cesarean delivery who had a term, singleton, cephalic gestation and reached complete dilation were analyzed. The duration of pushing, defined as the time from initiation of pushing to either vaginal delivery or the decision to proceed with a cesarean delivery, was determined. The primary maternal outcome was cesarean delivery and the primary neonatal outcome was a composite that included: mechanical ventilation, proven sepsis, brachial plexus palsy, clavicular fracture, skull fracture, other fracture, seizures, hypoxic–ischemic encephalopathy, or death. Nulliparous and parous women were analyzed separately in univariable and then multivariable analyses.

RESULTS: A total of 53,285 women were analyzed. In both nulliparous and parous women, longer duration of pushing was associated with increased odds of both cesarean delivery and the neonatal adverse outcome composite. Nevertheless, even after 4 hours of pushing, approximately 78% of nulliparous women who continued with active pushing had a vaginal delivery and more than 97% did not have the composite adverse neonatal outcome. Similarly, after more than 2 hours of pushing, approximately 82% of parous women who continued active pushing delivered vaginally and more than 97% did not have the adverse neonatal outcome.

CONCLUSION: A longer duration of pushing is associated with an increased relative risk, but small absolute difference in risk, of neonatal complications. Approximately 78% of nulliparous women delivered vaginally even after 4 hours of pushing.

Grobman WA, Bailit J, Yinglei L et al (2016). Association of the Duration of Active Pushing With Obstetric Outcomes. Obstetrics & Gynecology 127(4): 667-73. doi: 10.1097/AOG.0000000000001354


3. Does the Epi-No® birth trainer prevent vaginal birth-related pelvic floor trauma? A multicentre prospective randomised controlled trial.

I know from my workshops and from childbirth education experience that this one is controversial! Some of the early research in this area suggested that costly perineal ‘training’ devices might offer benefit, but some of the research was funded by the companies selling the devices, which means we need to be very careful before accepting the results. This recent independent trial of 660 women showed no clinical benefit to these devices. Other factors such as the potential for injury, the different hormones that women will experience in pregnancy and during labour and the effect that recommending such devices may have on a woman’s sense of her own body’s ability to birth also need to be taken into account. If I’m honest, though, I’m also a bit sceptical about whether using translabial ultrasound (as in the methods of the study itself) is fair, helpful or conducive to a woman’s sense that her body is capable of birthing without help.

Objective: Vaginal childbirth may result in levator ani injury secondary to overdistension during the second stage of labour. Other injuries include perineal and anal sphincter tears. Antepartum use of a birth trainer may prevent such injuries by altering the biomechanical properties of the pelvic floor. This study evaluates the effects of Epi-No® use on intrapartum pelvic floor trauma.

Design: Multicentre prospective randomised controlled trial.

Setting: Two tertiary obstetric units in Australia.

Population: Nulliparous women carrying an uncomplicated singleton term pregnancy.

Methods: Participants were assessed clinically and with 4D translabial ultrasound in the late third trimester, and again at 3–6 months postpartum. Women randomised to the intervention group were asked to use the Epi-No® device from 37 weeks of gestation until delivery.

Main outcome measures: Levator ani, anal sphincter, and perineal trauma diagnosed clinically and/or with translabial ultrasound imaging.

Results: Of 660 women randomised, 504 (76.4%) returned for assessment at a mean of 5 months postpartum. There was no significant difference in the incidence of levator avulsion [12 versus 15%; relative risk (RR) 0.82, 95% confidence interval (95% CI) 0.51–1.32; absolute risk reduction (ARR) 0.03, 95% CI −0.04 to 0.09; P = 0.39], irreversible hiatal overdistension (13 versus 15%; RR 0.86, 95% CI 0.52–1.42; ARR 0.02, 95% CI −0.05 to 0.09; P = 0.51), clinical anal sphincter trauma (7 versus 6%; RR 1.12, 95% CI 0.49–2.60; ARR –0.01, 95% CI −0.05 to 0.06; P = 0.77), and perineal tears (51 versus 53%; RR 0.96, 95% CI 0.78–1.17; ARR 0.02, 95% CI −0.08 to 0.13; P = 0.65). A marginally higher rate of significant defects of the external anal sphincter on ultrasound was observed in the intervention group (21 versus 14%; RR 1.44, 95% CI 0.97–2.20; ARR –0.06, 95% CI −0.13 to 0.05; P = 0.07).

Conclusion: Antenatal use of the Epi-No® device is unlikely to be clinically beneficial in the prevention of intrapartum levator ani damage, or anal sphincter and perineal trauma.

Atan IK, Shek KL, Langer S et al (2016). Does the Epi-No® birth trainer prevent vaginal birth-related pelvic floor trauma? A multicentre prospective randomised controlled trial. BJOG: An International Journal of Obstetrics and Gynaecology. Online version ahead of print. 29 February 2016.


4. A randomized controlled trial of abdominal binders for the management of postoperative pain and distress after cesarean delivery

Lastly, here’s another interesting study about an intervention that also divides women, midwives and birth folk – no pun intended! As I travel around the world, I meet some women and midwives who think that binders are brilliant, and others who think that they are a waste of time. I’ve not picked this particular study because it necessarily reflects my own view, because I have come to the conclusion that there probably isn’t one answer that suits everyone in this area, and that there are probably too many personal factors to be able to get a really good answer from research trials. But that shouldn’t stop us looking at trials; not least because they can teach us a lot about the pros and cons of using different methods to explore different practice-related questions.

Objective: To determine whether abdominal binders effectively control pain and distress after cesarean delivery.

Methods: A prospective randomized controlled trial was conducted between April and November, 2014, among women undergoing cesarean delivery (low-transverse skin incision) at two US hospitals. Participants were randomly allocated to either the abdominal binder or control groups on entry to the operating suite. Masking was not possible. Patients in the abdominal binder group were fitted with a device before leaving the operating room and were encouraged to wear it constantly, although breaks were allowed. The primary outcomes were postoperative distress (measured by the Symptom Distress Scale [SDS]) and pain (measured by a visual analog scale [VAS]). Individuals who asked to be removed from the study within 6 hours of surgery were excluded from analyses.

Results: Analyses included 87 patients in the abdominal binder group and 68 in the control group. The abdominal binder and control groups did not differ in postoperative day 1 VAS (3.1 ± 2.1 vs 3.4 ± 2.3; P = 0.33), postoperative day 2 VAS (3.0 ± 1.9 vs 3.8 ± 2.2; P = 0.16), postoperative day 1 SDS (21.5 ± 5.4 vs 21.8 ± 5.1; P = 0.87), and postoperative day 2 SDS (19.4 ± 4.8 vs 19.9 ± 5.0; P = 0.53).

Conclusion: Postoperative pain and distress scores after cesarean delivery were not affected by abdominal binders.

Gillier CM, Sparks JR, Kriner R et al (2016). A randomized controlled trial of abdominal binders for the management of postoperative pain and distress after cesarean delivery. International Journal of Gynecology & Obstetrics 133(2): 188–9
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