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\begin{document}

\title{Reported outcomes for planned caesarean section versus planned vaginal
birth in women aged 18-45: a systematic review}



\author[1]{Hui Wei Leow}%
\author[2]{Elizabeth Tan}%
\author[3]{Mairead Black}%
\affil[1]{The University of Edinburgh College of Medicine and Veterinary Medicine}%
\affil[2]{University of Aberdeen}%
\affil[3]{Aberdeen Maternity Hospital}%


\vspace{-1em}



  
  \date{May 26, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Background There is currently no consensus regarding the outcomes and
outcome measures that should be reported in studies assessing planned
mode of birth. Objectives To develop an inventory for reported outcomes
for studies comparing planned caesarean section (CS) and planned vaginal
delivery (VD) for women age 18-45. Search strategy Three online
databases, Ovid SP version of MEDLINE and EMBASE and the Cochrane
Pregnancy and Childbirth Group's Trials Register, were searched from
2011 to June 2019. Selection criteria The inclusion criteria were:
prospective studies evaluating planned mode of birth, age 18-45,
singleton pregnancy, gestational age 37-40 weeks, \textgreater{}100
participants, middle or high income countries. No language restrictions
were applied. Data collection and analysis Two researchers independently
screened titles and abstracts, and subsequently reviewed the full text
of each selected study to assess for eligibility. Discrepancies were
resolved by discussion with a third author. The selected studies were
evaluated using the MOMENT criteria. Outcomes and outcome measures were
systematically extracted and organised into an inventory. Main results
63 prospective studies including data from 6,397,310 women were
included. Based on the MOMENT score of 4 or more, 37 studies (59\%) were
of high quality. In total, 43 different primary outcomes and 79
different primary outcome measures were identified; 12 different
secondary outcomes and 31 secondary outcome measures were identified.
The primary outcome measurements and definitions of outcomes were
inconsistent. Conclusions Prospective studies evaluating outcomes of
planned mode of birth frequently report different primary outcomes and
outcome measures. Funding: None required%
\end{abstract}%



\sloppy


\textbf{Reported outcomes for planned caesarean section versus planned
vaginal birth in women aged 18-45: a systematic review}

Authors: Hui Wei Leow\textsuperscript{1}, Elizabeth Lilinn
Tan\textsuperscript{2}, Mairead Black\textsuperscript{2}

\begin{enumerate}
\tightlist
\item
  University of Edinburgh, \textbf{~} 47 Little France Crescent,
  Edinburgh EH16 4TJ
\item
  University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen AB25
  2ZD
\end{enumerate}

Contact:

Dr Hui Wei Leow dramandaleow@gmail.com

Ms Elizabeth Lilinn Tan lilinn.tan.16@abdn.ac.uk

Dr Mairead Black mairead.black@abdn.ac.uk

Corresponding author:

Dr Mairead Black

Room 6 Aberdeen Centre for Women's Health Research

Second floor, Aberdeen Maternity Hospital

Cornhill Road, Aberdeen, AB252ZD

Short running title: Reported outcomes for planned mode of birth



\textbf{Abstract}

\textbf{Background}

There is currently no consensus regarding the outcomes and outcome
measures that should be reported in studies assessing planned mode of
birth.

\textbf{Objectives}

To develop an inventory for reported outcomes for studies comparing
planned caesarean section (CS) and planned vaginal delivery (VD) for
women age 18-45.

\textbf{Search strategy}

Three online databases, Ovid SP version of MEDLINE and EMBASE and the
Cochrane Pregnancy and Childbirth Group's Trials Register, were searched
from 2011 to June 2019.

\textbf{Selection criteria}

The inclusion criteria were: prospective studies evaluating planned mode
of birth, age 18-45, singleton pregnancy, gestational age 37-40 weeks,
\textgreater{}100 participants, middle or high income countries. No
language restrictions were applied.

\textbf{Data collection and analysis}

Two researchers independently screened titles and abstracts, and
subsequently reviewed the full text of each selected study to assess for
eligibility. Discrepancies were resolved by discussion with a third
author. The selected studies were evaluated using the MOMENT criteria.
Outcomes and outcome measures were systematically extracted and
organised into an inventory.

\textbf{Main results}

63 prospective studies including data from 6,397,310 women were
included. Based on the MOMENT score of 4 or more, 37 studies (59\%) were
of high quality. In total, 43 different primary outcomes and 79
different primary outcome measures were identified; 12 different
secondary outcomes and 31 secondary outcome measures were identified.
The primary outcome measurements and definitions of outcomes were
inconsistent.

\textbf{Conclusions}

Prospective studies evaluating outcomes of planned mode of birth
frequently report different primary outcomes and outcome measures.

\textbf{Funding:} None required

\textbf{Keywords:} Caesarean section; vaginal delivery; pregnancy;
systematic review; core outcomes; outcome harmonization; outcome
variation; COMET; CROWN initiative

(Abstract max 250 words)

\textbf{PROSPERO registration} : CRD42019133104.

\textbf{Tweetable abstract}

Reported outcomes and outcome measures of planned mode of birth studies
are inconsistent and require standardisation. (110 characters max)

\textbf{Background}

Planned caesarean section (CS) is poorly understood as studies reporting
CS outcomes often combine results for emergency and planned CS or
compare outcomes with actual vaginal births only. This represents a
substantial gap in knowledge as the alternative to planned CS is to plan
a vaginal birth. As emergency CS is usually an outcome of planning
vaginal birth, it is critical that the outcome of planned and emergency
CS are analysed separately. Given that CS rate is rising progressively
with reported rates of 24.5\% in Western Europe and 32\% in North
America, there is a need for high quality evidence comparing planned CS
to planned VD \textsuperscript{1-4}.

There is no consensus among patients, healthcare professionals and
researchers regarding the outcome measures that should be collected and
reported in studies assessing planned mode of birth. In absence of a
standardised approach, researchers can only make arbitrary decisions
when choosing among several important outcomes \textsuperscript{5}.
Furthermore, reporting bias can occur if the outcome is selected
retrospectively based on statistical significance of
results\textsuperscript{6}. In order for future studies to be comparable
and for results to be usefully combined, it is crucial for reporting of
outcomes to be consistent \textsuperscript{7}.

Core outcome sets capture the key outcomes based on what key
stakeholders (clinicians, patients, their partners, researchers, service
developers, funding organisations) consider important in the management
or prevention of a condition \textsuperscript{8, 9}. Ideally, the
primary outcome and other outcomes of a trial will be selected from a
core outcome set if available, but researchers may continue to explore
other outcomes and are not restricted to the outcomes in the core
outcome set \textsuperscript{9}.The RCOG and Royal Australian and New
Zealand College of Obstetricians and Gynaecologists (RANZCOG) has formed
the Core Outcomes in Women's and Newborn's Health (CROWN) initiative,
which is supported by 80 journals, to tackle unwarranted variation in
outcome reporting by encouraging the publication of studies reporting
outcomes from a core outcome set where available \textsuperscript{10,
11}.

For a meaningful core outcome set for planned mode of birth to be
developed, evaluation of reported outcomes and outcome measures across
published studies is required \textsuperscript{12}. The aim of the
present study was to identify and organise the outcomes and outcome
measures reported in prospective studies investigating planned mode of
birth.

\textbf{Methods}

A protocol including study selection criteria and data extraction
methods was developed. The systematic review was registered with the
International Prospective Register of Systematic Reviews (PROSPERO)
(registration number: CRD42019133104; Available from:
https://www.crd.york.ac.uk/prospero/display\_record.php?ID=CRD42019133104;
Registered on 04 September 2019), and was conducted in accordance with
the Preferred Reporting Items for Systematic Reviews and Meta-Analyses
(PRISMA) statement \textsuperscript{13}. Ethical approval was not
required for this study. This study did not require any funding.

\textbf{Search methods for identification of studies}

The review was undertaken by searching the Ovid SP version of MEDLINE
and EMBASE and the Cochrane Pregnancy and Childbirth Group's Trials
Register from 2011 to June 2019, followed by a manual search of
references of relevant articles (reviews) and clinical guidelines (ACOG,
NICE, UpToDate) for eligible studies. The length of the review period
was restricted to 2011 to June 2019 because NICE clinical guideline for
planned CS was updated in 2011 and scoping work showed that this
guideline would enable identification of all relevant studies to capture
the most important outcomes up until that date. The search strategy used
in electronic databases was based upon a combination of terms relating
to caesarean section; vaginal birth; and planned (Appendix S1).
Abstracts and conference proceedings were excluded because of the high
probability of incomplete data. Citations were collated using EndNote X9
and Microsoft Excel and duplicates were removed.

\textbf{Study selection}

The inclusion and exclusion criteria of the study are as in Table 1.
Only prospective studies reporting clinical outcomes of planned CS
versus planned vaginal birth at term for singleton pregnancy were
included. All cases where vaginal birth was the intended birth route
regardless of whether this resulted in emergency caesarean section,
forceps delivery, ventouse delivery or spontaneous vaginal birth were
included. Studies that classified women with planned VD who eventually
had planned VD, and women with planned VD who eventually had emergency
CS as separate interventions were included. This is because these
studies added value to our overall objective of collecting core outcome
and outcome measurements, and our review did not assess results of
outcomes between the two different groups of planned VD including
emergency birth versus planned CS, where incomplete groups would lead be
a major weakness.

Outcomes reported for multiple pregnancy, preterm birth and vaginal
birth after CS (VBAC), also known as trial of labour after CS (TOLAC),
were not included as these topics would warrant separate core outcome
sets \textsuperscript{14, 15}. Studies investigating placenta praevia,
HIV infection, contracted pelvis were excluded as these were clear
indications for CS. Abstracts, reviews and conference proceedings were
excluded. Retrospective studies were excluded due to high risk of
reporting bias. Studies comparing planned mode of birth of second
pregnancy versus first pregnancy were excluded as they were not
explicitly comparing planned CS versus planned VD. There were no
language restrictions.

\textbf{Data extraction and management}

Two researchers (HWL, ELT) independently screened titles and abstracts,
and subsequently reviewed the full text of each selected study to assess
for eligibility. Any discrepancies in initial screening between the two
researchers were resolved by discussion with a third author (MB). The
following data were extracted from the selected studies: participant
demographics (sample size, age, geographic), study design, interventions
(spontaneous vaginal delivery (SVD), operative VD, planned/ elective CS
or unplanned/ emergency CS), primary and secondary outcomes, outcome
measures and definitions (if given). If the primary outcome was not
stated explicitly, the main outcome reported in the conclusion or the
outcome included in the study's power calculation was recorded. The
authors of the studies were not contacted to clarify the details of
primary outcome. The composite outcomes were recorded in the extraction
of outcomes.

\textbf{Quality assessment}

The outcome quality was scored according to the MOMENT criteria
(Management of otitis media with effusion in cleft palate score system)
in a 6-point scale. The MOMENT criteria is a validated checklist used
for quality assessment at study level which has been employed in a
previous core outcome set development for women's health and asks the
following \textsuperscript{16, 17}: was a primary outcome stated (one
point); was the primary outcome clearly defined for reproducible
measures (one point); were the secondary outcomes clearly stated (one
point); were the secondary outcomes clearly defined for reproducible
measures (one point); do the authors explain the choice of outcome (one
point); and are the methods used designed to enhance quality of measures
appropriate (one point) \textsuperscript{18}. High quality was
determined for studies that reached score 4 or more in these criteria.
Although composite outcomes were recorded, they were not scored as
primary outcomes because they are known to be frequently unreasonably
combined, inconsistently defined and inadequately
reported\textsuperscript{19}.

For this review, the studies were not excluded based on their quality as
the aim of this review was not to assess efficacy or causal associations
of mode of birth on outcomes, but simply to provide a summary of
outcomes reported in previous studies, and therefore was not considered
to be affected by study quality.

\textbf{Data analyses}

The identified outcomes were organised into an inventory based on the
outcome measures and quality of the studies. The total number of
individual outcomes and the frequency of each reported outcome were
calculated and definitions of outcomes were analysed. The outcomes were
reviewed to reduce duplication caused by different terminologies and
similar outcomes were grouped together to create a clear and succinct
outcome inventory. A narrative synthesis was performed in addition to
the summative analysis. The outcomes were organised into broad
categories: maternal and neonatal short-term and long-term outcomes and
subsequent pregnancy outcomes. The short-term outcomes were defined as
outcomes less than one year after delivery and long-term outcomes as one
year or more.

\textbf{Results}

In total, 1878 titles and abstracts were screened, 99 potentially
relevant studies were examined in detail (Figure 1). 63 prospective
studies (two case-control studies, 48 cohort studies, 7 cross-sectional
studies, 6 observational studies) reporting data from 6,397,310 women
met the inclusion criteria (Appendix S2). All studies reported outcomes
comparing planned mode of birth, 36 studies also reported outcomes for
emergency CS (57\%), 17 studies also reported outcomes for assisted VD,
8 studies reported outcomes for planned VD vs CS for breech birth (13\%)
(Appendix S2).

Based on the MOMENT score of 4 or more, 37 studies (59\%) were of high
quality (Appendix S3). The primary outcome was clearly stated in 50
studies (79\%), 49 studies (78\%) had reproducible primary outcome
measures. 11 studies reported secondary outcomes (18\%), 6 (10\%)
studies had reproducible secondary outcome measures. In 51 studies
(81\%), the authors explained the choice of outcomes selected. 46
studies (73\%) employed methods to enhance quality of measures by
suitable training, repetition, or adjusting for confounding factors. 3
studies reported composite outcomes studying childhood adverse
neurodevelopmental outcome, neonatal morbidity outcomes, and maternal
and neonatal complications (Appendix S3) \textsuperscript{20-22}.

In total, 43 different primary outcomes and 79 different primary outcome
measures were identified; 12 different secondary outcomes and 31
secondary outcome measures were identified (Table 2). The most reported
outcomes were maternal short-term outcomes (n=26 outcomes), followed by
childhood long-term outcomes (n=11 outcomes), neonatal short-term
outcomes (n=9), maternal long-term outcomes (n=8), and subsequent
pregnancy outcomes (n=1) (Table 2).

The primary outcomes and secondary outcomes were organised into an
inventory (Table 3; Table S1 and S2). Maternal primary outcomes were
organised into broad categories (Table S1): maternal experiences and
feelings (n=11 studies), genitourinary symptoms (n=9), postpartum
complications/ morbidity (n=9), maternal experiences and feelings
(n=11), breastfeeding (n=5) and hormone levels (n=1). The most reported
primary maternal outcomes were breastfeeding (n=5 studies, 8\%) and
postpartum depression (n=6 studies, 10\%). Neonatal outcomes were
organised into broad categories: baseline measurements (n=10 studies)
and morbidity (n=7). The most reported outcome measurements were
baseline measurements such as SpO2, HR, cord blood pH after birth and
APGAR score (Table S1). Childhood long-term outcomes were categorised
into different health conditions (metabolic diseases, n=4; respiratory,
n=4) and neurodevelopmental outcomes (n=9 studies). Two studies looked
into maternal subsequent pregnancy outcomes (Table S1).

The secondary maternal outcomes were organised into broad categories
(Table S2): genitourinary complications (n=7 studies), maternal
experiences and feelings (n=3), maternal morbidities (n=2),
breastfeeding (n=2) and baseline measurements (n=1). The most reported
outcome was anal and urinary incontinence (n=3). Two studies reported
secondary neonatal outcomes and one study reported childhood long-term
outcomes. Various scales/ questionnaires were used to measure maternal
primary outcome measures (n=15 scales/ questionnaires), childhood
primary outcome measures (n=2), maternal secondary outcome measures
(n=5), childhood secondary outcome measure (n=1) (Table 4).

\textbf{Discussion}

\textbf{Main findings}

This systematic review demonstrated a wide variation in reported
outcomes and outcome measures in most studies investigating planned mode
of birth. 63 prospective studies including data from 6,397,310 women
were include. 79\% of the studies reported a primary outcome. Among the
reported outcomes, maternal outcomes were the most reported ones (47\%),
followed by childhood long-term outcomes (20\%), neonatal short-term
outcomes (16.4\%), maternal long-term outcomes (14.6\%) and subsequent
pregnancy outcomes (1.8\%) (Table 2). This variation in outcome
reporting could be due to differences in ease of data collection for
long-term outcomes compared to short-term outcomes for maternal health,
whereas for neonatal outcome, immediate outcomes may be more easily
collected than to follow-up with children's long-term health. Only one
subsequent pregnancy outcome was recorded but this could be due to the
nature of this systematic review that only studies comparing planned CS
versus planned VD were included rather than studies comparing first and
second pregnancy. The variation in outcome reporting and outcome
measures means that individual studies cannot be compared and combined
in a meta-analysis of outcomes of planned mode of birth, thereby
limiting its usefulness to inform clinical practice.

\textbf{Strengths and Limitations}

To our knowledge, this is the first systematic review to identify key
outcomes reported in studies evaluating planned mode of birth. The
strengths of the present study include its comprehensive search strategy
and methodological design following methodology of previous publications
in this field \textsuperscript{12, 23}. To prevent bias in the review
process, study selection was conducted independently by two researchers
and discrepancies were resolved through discussion. However, the
exclusion of retrospective studies and strict inclusion criteria meant
that certain useful reported outcomes may have been omitted. Whilst it
may be useful to review retrospective trials, the outcome selections in
retrospective trials could be influenced by many factors, including
finances and time frame, and tend to have reporting bias, therefore
affecting the quality of outcomes and outcome measures selected. The
high prevalence of reporting bias could have an impact on the
conclusions in Cochrane reviews \textsuperscript{24}. Given that up to
85\% of studies are wasted throughout various stages of research,
accumulating a loss of tens of billions of dollars of investment in
research annually, improved methodological input for research design at
an early stage, such as selecting appropriate outcomes, is
detrimental\textsuperscript{25}.

\textbf{Interpretation}

The next challenge is to address poor outcome reporting by developing a
core outcome set for planned mode of birth. By selecting key outcomes
from a core outcome set and using appropriate outcome measures, future
studies can reduce inconsistency for outcome reporting, and can thereby
improve clinical usefulness of studies \textsuperscript{8}. Core outcome
sets may be developed with use of the modified Delphi survey where key
stakeholders including patients are involved in selecting important
reporting outcomes, followed by consensus discussions\textsuperscript{8,
23}. The Core Outcome Measures in Effectiveness Trials (COMET)
initiative advocate for patient and public involvement in the
development of core outcome sets because their contribution towards the
understanding of important outcomes is essential in the development of
patient-centred core outcome sets \textsuperscript{9}. The development
of core outcome sets is supported by Cochrane Reviews of the effects of
healthcare interventions and by the World Health Organisation (WHO) in
developing guideline recommendations \textsuperscript{7}.

Across women's health, several core outcome sets, including
pre-eclampsia, endometriosis and infertility, have been
developed\textsuperscript{12, 23, 26, 27}. The successful implementation
of a core outcome set for rheumatoid arthritis has been shown to improve
harmonisation of research by establishing outcomes that are now more
frequently measured by researchers \textsuperscript{24}.

This study demonstrates that the reporting outcomes for planned mode of
birth is inconsistent and requires standardisation. There is no
internationally agreed selection of outcomes for studies evaluating
planned mode of birth. Future trials should select the primary outcome
from the core outcome set alongside other outcomes. This will improve
possibility of comparing and combining outcomes from different studies
for meta-analyses and will reduce reporting bias \textsuperscript{28}.

\textbf{Conclusion}

In conclusion, there is lack of standardised outcomes and outcome
reporting measures among prospective studies evaluating planned mode of
birth. The development of a core outcome set for planned mode of birth
is necessary to facilitate consistent reporting, to improve possibility
of comparing and combining results, to yield high quality evidence and
to improve patient care.

\textbf{Acknowledgements}

We thank Donna Watson (University of Edinburgh) for librarian advice for
systematic review search strategy.

\textbf{Disclosure}

HWL, ELT and MB have no conflicts of interest.

\textbf{Author contributions}

HWL and MB contributed to conception and design of the study protocol.
HWL and ELT extracted data and analysed the results. HWL, ELT and MB
drafted and revised the manuscript. All authors gave final approval for
the manuscript to be published.

\textbf{Ethical approval}

Not required

\textbf{Funding}

None

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