Historically, the greatest decrease in perinatal mortality from vaginal breech deliveries was reported by Bracht in 1938.20
Other techniques recommended to enhance the safety of vaginal breech delivery include routine determination of fetal weight, head attitude, and nuchal or presenting cord using ultrasonography; continuous fetal monitoring; radiological pelvimetry; cautious attention to the progress of labour; and preparing for emergency symphysiotomy should fetal parts become trapped.21
Although poorly amenable to scientific analysis, some of these techniques are likely to be important for safe vaginal breech delivery. None were included in the term breech trial.
It is impractical for a large, multicentre trial to use complex risk reducing strategies. Meaningful quality control in 121 centres is impossible, and more caution would have meant fewer vaginal deliveries, increasing the number of participants needed to achieve similar statistical power. Therefore, the researchers chose a simple labour protocol with few risk avoidance strategies. The lack of proved effectiveness of other strategies ostensibly justified their exclusion; yet our current inability to analyse safe vaginal breech delivery does not preclude its existence. The resulting standard of care, arguably reasonable for a large, multicentre trial, falls short of its designation as the definitive study of vaginal breech delivery.
Since publication of the term breech trial, the onus has been placed on individual obstetrical units to retrospectively examine their experience with vaginal breech delivery and to show safety. Several have done so and continue to offer vaginal breech delivery.11,22,23
Safety in these specific centres is due to heterogeneity of human skill, not to statistical anomaly, and vaginal breech delivery in those units should be studied and emulated. For complex phenomena, a large, randomised, multicentre trial does not overrule demonstrated safety.
In the case of carotid endarterectomy, it should ideally be performed at a centre and by a surgeon with a perioperative stroke rate of 3%, not 6%. If unavailable, a patient might elect medical treatment, as the risks could outweigh the benefits. Similarly, a woman with an average breech presentation and access to average care may decide that a caesarean section is safer than a trial of labour; yet even that conclusion is potentially flawed: without a bias of licence, the maternity unit caring for her may well have a low, safe, baseline vaginal breech delivery rate.