CTG monitoring involves the collection of information about the fetal heart rate and the woman’s uterine activity. Until recently, there have been two ways to gather heart rate information (external Doppler sensor or internal fetal spiral electrode to record an ECG signal) and two ways to gather contraction information (external tocodynamometer or intrauterine pressure catheter). The externally worn approaches have issues with “loss of contact”, or periods of time when data are not recorded. The internal monitors have less of a problem with this, but are invasive and increase the risk of infection (among other things).
A new approach to CTG monitoring has started to be used in clinical practice. It has been designed in an attempt to achieve the best of both worlds. To gather information about the heart rate, fetal ECG monitoring is used, but with an externally worn sensor. Information about what the woman’s uterus is up to is gathered from an externally worn sensor measuring electrical activity in the uterine muscle, known as electrohysterography or EHG.
Several different manufacturers now offer products for clinical use. All the ones I have seen so far make use of an array of adhesive pads containing the sensors, and a rechargeable and detachable transmitter that clicks into place within the array. This makes the system both beltless (no straps are needed to hold the sensors in place) and wireless (no need for a physical connection between the woman’s body and the CTG machine). I believe they are shower proof, but are not suitable for use during water immersion in a birth pool.
Potential pros and cons
You would expect that a beltless system would be more comfortable, and being wireless would facilitate freedom of movement during labour. Both these might mean women could experience their labour pain more favourably than with other approaches to CTG monitoring. It might also translate into reduced use of caesarean section. Using fetal ECG and EMG data should reduce the incidence and duration of periods of loss of contact, improving the interpretability of the trace. There are a lot of coulds and shoulds here because we don’t yet have much data about this.
However, these noninvasive ECG/EHG combinations are still CTG monitoring. They might use different approaches to gather data, but it is still the same information being collected. It is difficult to imagine how they might go about improving perinatal outcomes, given that this hasn’t been proven for other approaches to CTG monitoring.
We won’t really know what it is like, and what it can achieve, until someone has a go at it and does research. Fortunately, a team of Australian midwifery researchers (Deborah Fox, Rebecca Coddington, and Vanessa Scarf) have been working to gather information about this new technology. So far they have published findings from a feasibility study (Fox et al., 2021a), a survey of maternity services in Australia and New Zealand about the availability of wireless / beltless monitors (Fox, et al., 2021b), and midwives experiences of caring for women using one particular monitor (the Phillips Avalon Beltless Fetal Monitoring Solution) in one Australian hospital (Fox, et al., 2022). I have previously written a blog post about this last one – available here.
To this collection, they have now added a paper outlining the experiences of women who made use of this new technology during the feasibility study (Coddington, et al., 2023). Fifteen women were interviewed. Most had previous experience of CTG monitoring using older technologies, from either a previous labour or from antenatal CTG monitoring.
Women described the beltless / wireless monitoring system as far superior in terms of comfort:
You don’t really notice it’s there… It’s just one less thing that you really had to think aboutKara, p. 3
Using the new system did appear to translate to better freedom of movement for some women than they had experienced with traditional CTG monitoring equipment:
I was getting anxious that I wanted to get up. But it was just too difficult with the belt on. So, I was feeling a bit anxious about having that feeling again … that was totally alleviated with the beltless systemMelanie p. 4
Many women appreciated being able to freely move to use the bathroom without needing to request assistance with monitoring equipment:
I was feeling really anxious about not being able to move with my second birth. So, just being able to get up. And I vomited during both births. So being able to actually get up and vomit was rather good rather than just laying back.Melanie p. 4
When the adhesive array worked well, it did not need further adjustment during labour. But this wasn’t always the case for all the women interviewed. When adjustments were needed, they had the potential to disturb the woman in a way that is similar to conventional CTG monitoring:
There were a lot of people poking and prodding and trying to adjust [the sensors on the beltless system] during contractions, when I was mentally trying very hard to focus on breathing. I felt like there were stressors around me and I was picking up on midwives being a bit anxious… Having someone fiddling with me and talking to me and saying, “I’ll just get you to move this way and just get you to move that way,” was pulling me out of where I mentally needed to be.Natasha p. 5
This small study shows some improvements in comfort and mobility with the new beltless / wireless approach to gathering CTG data. This is a useful additional to our knowledge base. Further research on larger groups of more diverse women, and information about impacts on clinical outcomes like analgesia use, labour duration, and mode of birth would be welcome.
Coddington, R., Scarf, V., & Fox, D. (2023, Mar 14). Australian women’s experiences of wearing a non-invasive fetal electrocardiography (NIFECG) device during labour. Women & Birth, in press. https://doi.org/10.1016/j.wombi.2023.03.005
Fox, D., Coddington, R., Scarf, V., Bisits, A., Lainchbury, A., Woodworth, R., Maude, R., Foureur, M., & Sandall, J. (2021a). Harnessing technology to enable all women mobility in labour and birth: feasibility of implementing beltless non-invasive fetal ECG applying the NASSS framework. Pilot & Feasibility Studies, 7(1), 214. https://doi.org/10.1186/s40814-021-00953-6
Fox, D., Maude, R., Coddington, R., Woodworth, R., Scarf, V., Watson, K., & Foureur, M. (2021b). The use of continuous foetal monitoring technologies that enable mobility in labour for women with complex pregnancies: A survey of Australian and New Zealand hospitals. Midwifery, 93, 102887. https://doi.org/10.1016/j.midw.2020.102887
Fox, D., Coddington, R., & Scarf, V. (2022). Wanting to be ‘with woman’, not with machine: Midwives’ experiences of caring for women being continuously monitored in labour. Women & Birth, 35(4), 387-393. https://doi.org/10.1016/j.wombi.2021.09.002
Categories: CTG, EFM, New research
Tags: Beltless, fECG, fetal ECG, telemetry
Both these might mean women could experience their labour pain more favourably that with other approaches
Another interesting post. Will add experiences paper to my dissertation set.
Sent from my iPad
Thank you for your eagle eye! I’ll go correct it.