The Term Breech Trial
/Actual title: Planned cesarean section versus planned vaginal birth for breech presentation at term: a randomized multicenter trial
Background:
Who did the study, and who published it?
Another large collaborative group study – the Term Breech Trial Collaborative Group
Primary authors of the group based in Canada
Participating sites spanned Europe, Canada, Australia, Central/South America, Africa, Middle-East, India & Pakistan
Funded by Canadian Institutes of Health Research (like Canada’s NIH)
Why was the study done?
As we covered in our ECV and breech birth podcasts, breech presentation affects about 3-4% of term pregnancies.
At the time this was conducted (published in 2000), it was a controversial question for delivery approach:
Cohort studies prior to this trial suggested that cesarean section was potentially better.
However, these cohort studies were potentially confounded by inclusion of pregnancies that would not be considered for breech birth (i.e., footling presentation) or by lack of experience with breech deliveries by the participating physicians.
Two smaller RCTs prior to this trial and a meta-analysis did not find any substantial benefit to planned cesarean.
Thus this ambitious trial was carried out to determine which was truly better.
What was the research question?
“To determine whether planned cesarean section was better than planned vaginal birth for selected fetuses in the breech presentation at term.”
Methods:
Who participated and when?
Enrollment between Jan 1997 and April 2000 at 121 centers in 26 countries.
Eligibility:
Breech presentation at or after 37 weeks → assigned to planned cesarean or planned vaginal delivery after consent by telephone system.
If assigned to CD group: planned CD was scheduled for 38+ weeks.
If patient presented in labor, CD was performed as soon as possible.
Presentation was confirmed again prior to cesarean and if cephalic, vaginal birth was then planned.
If assigned to VD group: management was expectant until spontaneous labor began, unless an indication to induce labor or a different reason for cesarean developed.
Labor management protocol was standardized (a LOT of standards):
Induction and amniotomy were allowed for standard OB indications
FHR monitoring by intermittent auscultation or cEFM
Augmentation with oxytocin was permitted, “so long as the clinician was confident that there was no evidence of cephalopelvic disproportion.”
Adequate labor progress in 1st stage was 0.5cm/h after onset of active labor, and in 2nd stage was descent of breech to pelvic floor within 2hr of full dilation, and delivery being imminent within 1hr of active pushing.
If fetal heart rate abnormalities were encountered or lack of progress in labor occurred, CD was performed.
Anesthesia choice was left to patient and providers.
Delivery means was recommended to have no intervention until spontaneous exit of the infant to the umbilicus, and minimum intervention thereafter with no traction on the body; and controlled delivery of the head using forceps or Mariceau-Smellie-Veit maneuver.
Total breech extraction was not permitted.
Deliveries were to be attended by an “experienced clinician” – defined as someone who considered themselves to be skilled and experienced at vaginal breech delivery and confirmed by their department head at their institution.
Each clinician was assigned a code number prior to study enrollment and there was info recorded on their qualifications and years of experience with breech delivery.
What were they looking for?
Primary outcome: perinatal or neonatal mortality at less than 28 days of age, or one or more serious neonatal morbidities such as:
Birth trauma, such as subdural hematoma, IVH, spinal cord injury, basal skull fracture, peripheral nerve injury, or clinically significant genital injury;
Seizures at less than 24h of age or requiring 2+ drugs to control;
Apgar of less than 4 at 5 mins
Cord base deficit of 15 or greater
Hypotonia for at least 2 hours
Stupor, decreased response to pain, or coma
Intubation and ventilation for at least 24h
Tube feeding for four days or more
NICU admission longer than 4 days
Secondary outcome: maternal mortality or serious maternal morbidity for up to six weeks postpartum, such as:
PPH > 1500 cc or need for transfusion
D&C for bleeding or retained tissue
Hysterectomy
Cervical laceration involving lower uterine segment (if SVD)
Vertical incision or serious hysterotomy extension (if CD)
Vulvar or perineal hematoma requiring evacuation
DVT / PE
Pneumonia, ARDS
Wound infection requiring prolonged hospital stay, wound breakdown
Bladder / ureter / bowel injury requiring repair, or development of fistula
Bowel obstruction
Other serious morbidities
They also used multiple logistic-regression analyses to test for interactions between demographic / baseline characteristics and outcomes:
I.e., looking at the perinatal outcomes for babies, looked at interaction with maternal age, parity, type of breech presentation, gestational age, labor vs induction, EFW by US vs Leopold’s, etc.
They also looked at center’s standard of care in “usual care” vs “high standard of care” environments (as determined by a pre-study survey) and maternal/perinatal mortality rate in the center’s country
High standard of care was defined as:
Having ability to perform a cesarean within 10 mins (vs 60 mins)
Personnel to bag-mask a baby available immediately (vs 10 mins)
Personnel to intubate / provide PPV to baby within 10 mins (vs 30 mins)
Ability to ventilate a baby for >24h (vs need for transfer for this)
Results:
Who was recruited?
2088 pregnant patients were randomized, with 1043 assigned to CD and 1045 assigned to VD
Maternal outcomes were available for 1041 (CD) and 1042 (VD) groups
Neonatal outcomes were available for 1039 (CD) and 1039 (VD) groups
Overall very low loss to follow up!
Groups were overall very similar:
52% in each group were nulliparous
EFW > 3kg in ~66% in each group (with 60% in each group estimated by ultrasound)
21.9% in each group underwent attempted ECV
35% of deliveries in each arm took place in “high standard of care” centers.
~42% in each group presented in labor, and ~23% in each group had membranes ruptured on presentation.
Median GA at delivery was similar in each group (39w3d CD vs 39w6d VD)
In the planned CD group:
90% had a CD, and 10% had a VD
In the planned VD group:
43.3% had a CD, and 56.7% had a VD
CDs most commonly performed for:
Fetopelvic disproportion or abnormal progress in labor (50.1%)
Fetal heart rate abnormality (28.6%)
Footling breech presentation (15.3%)
Patient request (13.5%)
Medical or OB complication (10%)
Cord prolapse (2.7%)
~15% of labor was induced, and ~50% of labor was augmented.
Only 9% had a protocol violation of labor management:
3.6% for prolonged labor
1.4% for footling or uncertain presentation of breech at delivery
2.7% had no experienced clinician at delivery
Outcomes:
Primary
There was a significantly lower risk of perinatal/neonatal morbidity in the planned cesarean group:
17/1039 (1.6%) CD vs 52/1039 (5.0%) VD (RR 0.33)
This held true in both countries with low perinatal mortality rates and high perinatal mortality rates.
This difference lessened (but remained statistically significant) with increasing experience of the attending provider – that is, there was less risk of morbidity when more experienced personnel were present.
This difference also lessened (but remained statistically significant) when excluding induced/augmented labor, deliveries without a skilled clinician, and those with footling/uncertain breech presentation
Bottom line: there is higher perinatal morbidity with planned VD, despite increasingly optimal environments in subanalyses
There were 3 neonatal deaths in the cesarean group, and 13 in the vaginal delivery group.
One of the CD group deaths was actually a vaginal birth with difficult delivery.
Two of the vaginal birth deaths were likely prior to enrollment; two were of neonates discharged from the hospital in good condition otherwise; and two were suspected intrapartum demises before a cesarean section could be started.
The reduction in perinatal morbidity was much greater in countries with lower perinatal mortality rates, despite a higher likelihood of cesarean birth in the VD groups in those countries
I.e., in an area with low perinatal mortality and a higher likelihood to get cut intrapartum, the benefit of planned CD was even greater
There was more birth trauma, seizures, hypotonia, low Apgars, cord blood acidemia, need for mechanical ventilation, and longer NICU stays in the planned vaignal delivery group.
Birth weight over 4000g was more likely in the VD group (5.8% vs 3.1%).
Secondary
No major group differences in maternal morbidity/mortality.
Impact
What was the impact of all of this, and what are we doing now?
Well you kind of know already – how many planned breech births have you done?
For most of us, that answer is probably 0 “planned” and maybe 1 or 2 “unplanned.”
This was absolutely a practice-changing paper – and has guided how we approach the patient with breech presentation at term ever since.
What criticisms exist of this trial?
High number of patients were randomized in labor, and questionable counseling:
~42% in each arm – this begs the question about how “planned” each method actually was, and how much counseling or selectivity may have been realistically applied to each patient.
Can also see this in the higher rate of >4kg babies in the VD arm, as well as only 20% in each arm had an attempt at ECV.
Standard of care was not consistent
Continuous EFM (for better or worse) was not standard
Fetal weight and attitude of the head, while recorded for trial data, did not have to be assessed by US
Generalizability is hard to interpret with the pooled results:
I.e., would you take your chances on a breech in Australia with a well-counseled patient with CTG in a place where you can do a C-section in under 10 minutes and have highly qualified neonatal staff immediately available? Or in another location where you can’t do a c-section even by 60 minutes?
The subgroup analyses by perinatal mortality rate of countries tried to answer that, but it is curious they didn’t choose to divide it up by their “high standard” versus “usual standard” centers.
Subsequent analysis has shown that 30% of the morbidity/mortality in the VD group can be attributed to the 6.7% of vaginal deliveries attended by no experienced provider – also calling into question the impact of experience.
Enrollment scheme:
Units would call to centralized location to get allocation and this was not stratified by center – theoretically, a highly experienced obstetrician could call and end up with randomization to cesarean each time, and likewise an inexperienced one could call and randomize to vaginal delivery each time.
Numerous protocol violations and enrollment questions
Included initially in the trial were: 2 demised infants, 2 sets of twins, an anencephalic baby, a baby with spina bidfida, and another baby with suspected anomalies.
2 of the vaginal delivery group deaths were suspected to have been prior to randomization, yet counted in the perinatal mortality.
And a number of other deaths in the VD arm may not have been related to the delivery itself – i.e., SIDS, GI issues, anomalies, inadequate respiratory resuscitation or resources.
What about doing breech births? Can we? / should we?
We don’t recommend breech birth – that would be irresponsible to do outright!
Well counseled, well-selected patients in centers with experience in breech delivery, ability to perform cesarean, and provide immediate neonatal resuscitation – it may be reasonable, though this trial doesn’t totally answer that question based on problems with generalizability.
In the wake of this trial, the PREMODA study was performed in France and Belgium – a prospective observational study allowing providers to select mode of delivery where breech delivery was still an option/standard.
⅔ of women were allocated to cesarean delivery, but 71% of those undergoing planned vaginal breech birth were successful.
There was no difference in perinatal mortality/morbidity was noted between groups in this study – suggesting that rigorous protocols and assessment by those with experience may make breech birth safer.
Interesting critique of trial: https://www.ogmagazine.org.au/14/2-14/term-breech-trial/