In this study involving women with a single prior caesarean who had reached 37 wk gestation in their next pregnancy, and who did not have a contraindication to a planned VBAC, a plan to birth by ERC was associated with a beneficial reduction in the risk of fetal death or liveborn infant death prior to discharge or serious outcome for the infant, when compared with women who planned VBAC. For women planning a VBAC our 2.4% risk of death or serious outcome for the infant is similar to that reported from previous cohort studies that compared actual rather than planned mode of birth where risks ranged between 0.13% and 2.4% 
There are a number of strengths to our study design, enhancing the validity of our results. To our knowledge, this is the first randomised trial to report on health outcomes in this setting. However, few women consented to the randomised trial, as was suggested likely by our pre-trial survey of women's views 
. Although the randomised controlled trial is regarded as the “gold standard” research methodology for assessing the effects of health care interventions, some research questions cannot be fully answered using this design, particularly where patients have strong treatment preferences, and decline randomisation as in our setting. Given our experience here and the recognised difficulty of recruitment to randomised trials related to VBAC 
, it seems unlikely that large randomised trials will be conducted, although these may still be possible in other health care settings.
This is the first study designed around women's planned preferences for birth after caesarean, among women who were eligible for a VBAC, and therefore provides a high quality estimate of the benefits and harms associated with the two planned or intended treatment choices for birth, not previously reported. Most of the previous evidence has been based on comparison of actual mode of birth where groups were less comparable 
. Information relating to health outcomes for women and their infants is known for all 2,345 women enrolled in the study, and our sample size was sufficiently large to allow us to detect important, small differences between the two policies for care.
Flaws identified in the literature related to the risks and benefits of planned ERC and planned VBAC have included a lack of comparability of groups, specifically being unclear whether women included in the ERC group were truly eligible to attempt VBAC 
. Our study methodology ensured that all women recruited were considered eligible to attempt VBAC, on the basis of current clinical practice guidelines, as assessed by qualified staff at the time of study entry. We made a comprehensive assessment of known confounders with statistical adjustments for minor imbalances found between treatment groups for BMI, SES, and indication for previous caesarean. Nevertheless, unmeasured confounding may still account in part for the study findings. Our intention-to-treat analysis ensured that the study evaluated a policy of choice around planned ERC and planned VBAC.
We identified no increase in the risk of short-term maternal morbidity related to planned ERC, but rather a beneficial reduction in the risk of major maternal haemorrhage and/or the need for blood transfusion compared with planned VBAC. This finding is in sharp contrast to other reports where ERC has been associated with an increase in maternal blood loss 
and justifies further study.
The risk of symptomatic uterine scar rupture was low for both treatment groups being 0.1% for women in the planned ERC group and 0.2% for women in the planned VBAC group. This risk of uterine rupture related to VBAC is lower than that reported from the NICHD cohort study of 0.7% 
and lower than the rate of symptomatic uterine scar rupture of 1.2/100 to 3.9/1,000 among women having a VBAC reported in systematic reviews of other cohort studies 
. The standardised treatment schedules for VBAC and ERC, based on relevant evidence-based clinical practice guidelines used by all participating hospitals, may account for the low rates observed.
There is a well-documented increase in the risk of both perinatal mortality and infant morbidity with increasing gestational age beyond term 
. The differences in the risk of death or serious outcome for infants born to women in the planned VBAC group could be related to the difference in gestational age at birth observed between the two groups, rather than planned mode of birth. The relationship between advancing gestational age and morbidity and mortality, and the optimal time of birth for women at term therefore warrants further prospective evaluation.
Although statistically significant, overall the absolute risk difference in adverse health outcomes between the two forms of care remains small. Nevertheless, these small differences in the risk of short-term adverse health outcomes, either for the women or for their infants, are likely to be of considerable importance to the women, and therefore influence their choice of preferred mode of birth 
. Absolute risk differences (related to mode of birth) may vary by factor, such as previous successful vaginal birth, where planned VBAC is more likely to result in vaginal birth. Similar proportions of women in each treatment group had achieved a previous vaginal birth prior to the caesarean (13% in the planned ERC group and 15.6% in the planned VBAC group). There have been no studies comparing the risks and benefits of VBAC with ERC that have reported on the health outcomes beyond the neonatal period. This lack of information on long-term health of either VBAC or ERC should be included in the counselling provided to women to assist with their decision making.
There is a need to establish whether the identified short-term benefits in health and wellbeing persist or are balanced by later risks. Therefore the evaluation of longer-term health, for both the women and children in this study, will be important. Our planned longer-term follow-up at early school age will assess maternal and child health as well as outcome in subsequent pregnancies including the risk from multiple caesareans, such as placenta praevia and accreta, and fertility 
Our “restricted” prospective cohort study design used methodological features of high quality randomised trials, which included identification of a “zero time” for determining eligibility, study entry, and baseline characteristics; use of inclusion and exclusion criteria; treatment protocols derived from evidence-based clinical practice guidelines; standardised definitions for clinical outcomes; adjustment for imbalance in confounders at study entry; and the use of intention-to-treat analyses 
Our results, whilst not generalisable for other populations, indicate that for women who have had one previous caesarean birth and are considered eligible at term to attempt a planned VBAC in their next pregnancy, an ERC as planned mode of birth is significantly associated with a lower risk of both fetal death or liveborn infant death prior to discharge or serious infant morbidity and major maternal haemorrhage without increasing other maternal and perinatal complications. Women, clinicians, and policy makers can use this information to develop health advice to assist in making evidence-based decisions about care for women who have had a previous caesarean and their infants.