Last week I wrote about VBAC and its benefits and risks, this week I want to discuss choice of birthplace when choosing to labour after a previous Caesarean. If you haven’t yet read that post, I suggest you go back and build a good VBAC evidence foundation.
Let’s review the terminology:
Vaginal Birth After Caesarean
Trial Of Labour After Caesarean
(I am not a fan of this patronizing and condescending term, so you’ll see me continue to use more empowering terms)
Elective Repeat Caesarean Section
Not surprising, there’s not a lot of evidence in regards to VBAC at home. There’s really no money or funding for researchers looking at those outcomes.
The 2019 Society of Obstetricians and Gynaecologist’s (SOGC) TOLAC guideline has two recommendations that impact choice of birthplace for those labouring after a previous CS:
1) “TOLAC is optimal in an institution that has in-house OB, anesthesia and surgical staff and an immediate CS should be available. (Level III-B evidence)”
2) “Continuous Electronic Fetal Monitoring (EFM) is necessary as changes in the fetal heart rate are the best single marker of impending rupture (Level II.2-A evidence)“
Let’s dig into those two recommendations to see how they should impact your decision on choice of birthplace.
1) SOGC recommends access to immediate CS for all labouring VBACs
There is limited evidence on the interval of rupture to time of Caesarean in reducing poor outcomes for babies.
One study that’s relevant in this matter is a 2012 Utah study titled “Uterine rupture associated with VBAC”. For the purpose of presenting their evidence, I’ll use their language (i.e TOLAC, which you know I hate).
Utah has a similar population to Canada, with equal access to healthcare.
In this study, there were 12000 TOLACS, 36 cases of rupture (a rate of 0.32%), a TOLAC rate of 30% and VBAC rate of 85%. These rates are pretty similar to overall Canadian stats.
13 of the 36 ruptures had clinical signs of compromise in the newborns at time of birth (i.e these babies needed resuscitation or extra supports), but only 3 had long term deficits.
Those 3 babies who had long-term damage experienced births where there was more than 30 minutes from the time of rupture to Caesarean delivery.
This means that in this study, there was a 0.025% resulting risk of permanent brain damage in the 12000 women labouring.
No long term morbidity was found when the delivery was less than 30 minutes after rupture, however a time of less than 30 minutes didn’t prevent every case of short term negative outcomes in the newborns.
So according to the above study, each woman labouring after a previous CS had a 99.975% of avoiding brain damage in her baby, and that probability went to 100% when a CS was done within 30 minutes of rupture. That said, having quick access to the OR didn’t always prevent short-term problems in the baby.
You can see why the SOGC recommendation is actually a Level III – that’s expert opinion. NOT based on evidence! (Levels I and II are based on studies from the past.)
YOU are the best expert on your and your baby.
2) SOGC recommends EFM in labour for TOLACS
Let’s review the two ways we listen to a baby in labour:
With intermittent ascultation (IA), the care provider listens usually every 15-30 minutes in active labour and every 5 minutes while pushing.
Since the first sign of impending rupture is an abnormally low fetal heart rate, it is possible for the baby to have a significant change between heart rate checks.
According to the Association of Ontario Midwives 2021 VBAC Clinical Practice Guideline:
“Fetal heart rate monitoring may occur by:
• Intermittent auscultation q 15 minutes in active labour and q 5 minutes in the second stage; or
• Using continuous EFM per current protocols.
Prior to labour, the risks and benefits of IA and EFM should be discussed with clients and documented in their charts.”
“This recommendation recognizes the client as the primary decision-maker in their care. It recognizes midwives’ expertise in using IA and providing continuous one-to-one care.” (AOM)
If you just brushed up on your fetal monitoring knowledge by reading my previous post, you’ll see that Electronic Fetal Monitoring comes with it’s own risks, mainly increasing your risk of Caesarean. Which is exactly what you are trying to avoid, funny enough.
Take Home Lesson:
If you are planning a VBAC at home, be aware of the potential delay in diagnosis of a uterine rupture since intermittent auscultation is being used, and a potential delay in surgical intervention.
Dekker, R. “EBB 113: The Evidence on VBAC”. 28 January 2020. Podcast transcript. Evidence Based Birth.
Dy, J., DeMeester, S., Lipworth, H., Barrett, J. “No. 382-Trial of Labour After Caesarean”. 1 July 2019. Journal of Obstetrics and Gynaecology. Volume 41, Issue 7, P992-1011.
VBAC CPG Working Group. “Vaginal Birth After Previous Low-Segment Caesarean Section.” Association of Ontario Midwives. September 2011. Accessed 18 March 2021. Available at: https://www.ontariomidwives.ca/sites/default/files/CPG-Vaginal-birth-after-caesarean-section-PUB.pdf