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Does intrapartum CTG monitoring save lives?

Dr Kirsten Small is a project lead with the Transforming Maternity Care Collaborative. Yesterday she delivered the closing keynote address at the GOLD Obstetric Conference, speaking about why it is so difficult to align clinical practice with the research evidence. Kirsten hosts the Birth Small Talk blog and her post today reviews the research evidence she summarised in her address. She has kindly shared it here as well. 

If you are interested in pursuing research relating to the use of fetal heart rate monitoring in labour please connect with us via our contact form

 

Today’s post examines the research evidence about CTG monitoring with regards to stillbirth and neonatal death. This is a deep dive for my fellow data geeks who like to read the fine print, not the executive summary. The short version is – no. Using a CTG to monitor a woman in labour doesn’t prevent the death of her baby. If you are keen to know the details, read on!

Intrapartum CTG monitoring in low risk populations

This is the least controversial area of evidence, and the one most maternity clinicians are familiar with. Of the eleven randomised controlled trials that have compared CTG monitoring with intermittent auscultation (IA) during labour, three were done in low risk populations, five in high risk populations and the remaining three in mixed risk populations or where risk was not specified (Alfirevic et al., 2017).

The three low risk trials were Kelso et al., 1978, Leveno et al., 1986 and Wood et al., 1981. A total of 16,049 births were included in this analysis, which showed no statistically significant difference in the perinatal mortality rate (RR 0.87, 95% CI 0.29 – 2.58).

It has been almost 40 years since the last of these trials was performed. It could be argued that CTG technology has improved, or that we are better at CTG interpretation now. Heelan-Fancher et al. (2019) examined a large population data set from two states in the United States, specifically looking at birth outcomes for low risk women. This was not a randomised controlled trial – rather it was a non-experimental analysis of what happens in practice when women are monitored by CTG or by IA, with a very large sample size (1.5 million births). They didn’t report on intrapartum stillbirth. They found no significant difference in the neonatal mortality rate when CTG monitoring was used.

On the basis of available evidence, there is nothing that suggests that use of CTG monitoring rather than IA reduces the perinatal mortality rate in women considered to be at low risk. That’s not all that controversial. Most people in maternity care know this particular bit of information.

Intrapartum CTG monitoring in mixed, unknown, and high-risk populations

There is a widespread assumption that the absence of mortality benefit derived from CTG monitoring in labour ONLY applies to women considered to be low risk. We wouldn’t be using CTGs so widely if they didn’t save lives, right? But what does the evidence actually say regarding the use of intrapartum CTG monitoring in women who are not at low risk?

The randomised controlled trial evidence regarding high risk populations consists of five studies published over 6 papers, over a thirty-year period, starting in 1976 and continuing to 2006 (Haverkamp et al., 1979; Haverkamp et al., 1976; Luthy et al., 1987; Madaan and Trivedi, 2006; Renou et al., 1976; Shy et al., 1987). In addition, there are four studies published over five papers which were conducted in populations with both women considered to be at lower and higher risk or where the risk profile of the population was not described (Grant et al., 1989; Kelso et al., 1978; MacDonald et al., 1985; Neldam et al., 1986; Vintzileos et al., 1993). With my co-authors Associate Professor Mary Sidebotham, Professor Jenny Gamble, and Professor Jennifer Fenwick, we have synthesised the findings from these populations (Small et al., 2020).

In the high-risk population (n = 1,975), perinatal mortality was not significantly different when CTG was compared with IA (RR 1.17, 95% CI 0.62 – 2.22). There was also no statistically significant difference in mortality in the mixed-risk population (n = 15,994, RR 0.67, 95% CI 0.36 – 1.23). The mortality rate was higher in the mixed risk population than it was for the low risk population, and higher again for the high-risk population, indicating that researchers have correctly identified populations of women with higher risk.

Note that the number of women in the high-risk population is small. It has been argued that with a larger sample size a difference would be detected but that it would be unethical to recruit women considered to be a high-risk to further RCTs because the non-experimental evidence supporting the use of intrapartum CTG monitoring is so compelling. We set out to examine this assertion and examined the nonexperimental evidence (Small et al., 2020).

Non-experimental research

Our searches located 27 papers published between 1972 and 2018 which provided evidence about the use of intrapartum CTG monitoring in high-risk populations. We then used a tool (ROBINS-I) to assess the degree to which the findings of the research might be affected by bias – that is that the findings were due to something other than CTG use. 22 papers were at critical risk of bias and another was a serious risk. Most of these papers compared a time period prior to the introduction of CTG monitoring with a period after it was introduced, without controlling for any of the other changes to practice which might improve outcomes over time. Given the high risk of bias, the findings from these papers should not be relied on to guide practice as a consequence. The remaining five studies were assessed to be at moderate risk of bias. According to the ROBINS-I tool, studies at moderate risk of bias can be relied upon to inform clinical practice.

Starting with the studies at critical or serious risk of bias, only five of these studies showed a statistically significant reduction in perinatal mortality out of fourteen where this could be calculated. In the studies at moderate risk of bias (which ranged in size from 235 to 1.2 million women), no significant differences in perinatal mortality rates were reported. The argument that the non-experimental evidence presents a compelling argument for intrapartum CTG monitoring can’t be sustained on the basis of the available evidence.

Where to next?

Where does that leave us as clinicians and what recommendations can we make on the basis of these findings? We have an ethical obligation to include information regarding the lack of effectiveness of CTG monitoring in our discussions about intrapartum fetal monitoring with birthing women, regardless of their risk profile (Sartwelle et al., 2020) and to support their informed decision making. However, doing currently places clinicians at odds with professional guidelines. Professional guidelines are meant to be evidence informed, yet this is clearly not the case for intrapartum fetal monitoring. In order to support clinicians to provide evidence-informed care, there needs to be stronger recognition in professional guidelines that the evidence in favour of intrapartum CTG monitoring is far from compelling and that using IA instead is not proof of unprofessional practice.

The full reference list is available on the post on Birth Small Talk. 

 

Preventing stillbirth: What works best?

Preventing stillbirth has been, and continues to be, a major focus in both practice and research in maternity care. Reducing rates of stillbirth in high-income countries has proven challenging, with little significant change over the past two decades. One of the current approaches to tackle stillbirth has been to routinely and regularly encourage women to focus on the movement pattern of their fetus and report any changes to their maternity care provider. Is this the best approach, or might midwifery continuity of care be more effective?

Earlier this year Bellussi et al. (2020) published a systematic review of literature which addressed the question of whether heightened awareness of fetal  movement patterns reduces stillbirth. On the basis of the research available at that time, the answer was no – increasing awareness of fetal movements didn’t reduce the rate of stillbirth. Several large trials remained unreported at the time they conducted their analysis, and one of these has just been published.

The latest addition to the pool of evidence is the Mindfetalness study (Akselsson et al., 2020). Conducted in 67 maternity services in Sweden, individual clinics were randomly selected to provide either routine care, or to provide women written and verbal information about an approach they called Mindfetalness. Starting from 28 weeks of gestation, women were asked to spend 15 mins at rest daily, during a period of fetal activity, being mindful of the pattern of movements. Women were encouraged to “trust their intuition” and seek care if they were worried about the movement pattern.

A cluster-randomisation process was used to ensure that socio-economic status and the number of births conducted at the clinic didn’t influence the outcome. In total, 19,639 women were registered for care at clinics where Mindfetalness was used, and 20,226 in the control clinics. Stillbirth is a (fortunately) rare outcome, so astonishingly large studies are needed to examine any change in the outcome. Because of this, the more common occurrence of low Apgar scores (under seven at five minutes of age) was chosen as the outcome of interest, and the size of the study was planned to be big enough to confidently find an improvement of 4 fewer babies in every 1000 births having better Apgar scores, if this effect was present. Data were collected from women who gave birth after 32 weeks of gestation.

The rate of babies born with low Apgar scores was the same regardless of whether Mindfetalness was recommended or not (11 in every 1000 births). While the primary aim of the trial was not to look at deaths, they did collect this information. There was a slightly higher rate of stillbirth (2 in 1000) in the Mindfetalness group, than the control group (1.4 in 1000). No statistical measure was offered to judge whether this was a chance finding or not. Neonatal death was extremely low in both groups (1 and 2 in 10,000 respectively – not statistically different).

The abstract of the article highlights two benefits of the Mindfetalness approach. There was a statistically significant reduction in the caesarean section rate, from 20% to 19%. This is far from being a clinically significant difference, and it is far less than has been seen in other interventions proven to be effective for reducing the rate (for example introducing midwives into obstetric only maternity care models reduced the rate by 7% – Chen et al., 2018). The other benefit was a reduction in the rate of babies born under the tenth centile. This fell from 107 per 1000 to 102 per 1000. However, there was no difference in the more clinically relevant measure of the rate of babies born under the fifth centile.

The authors argue that “increasing women’s awareness of fetal movements is not harmful” (p.835). While this is true within the context of their research findings, widespread adoption of programs focusing on fetal movement as a means to reduce the stillbirth rate comes with an opportunity cost. Maternity systems have finite resources in terms of money, people, and time. Focussing efforts towards an ineffective but not harmful approach to care directs effort and people away from other approaches to care which are already known to be effective.

Much attention has focussed on reducing stillbirth close to the end of pregnancy. The relationship between gestational age and stillbirth is a ‘U’ shaped curve (Ibiebele et al., 2016). The rate rises beyond 36 weeks of pregnancy, but we often forget that it also is high prior to 24 weeks of gestation. Fetal movement monitoring will be entirely ineffective for this population of fetuses, as it presumes that achieving the birth of the baby will prevent death. This is not true in the time prior to viability.

We already have sound research evidence that the rate of deaths prior to and after birth before 24 weeks of gestation can be reduced – a 19% reduction from 32 deaths per 1000 births to 23 – which is both statistically and clinically significant. This can be achieved through midwife-led continuity of care (Sandall et al., 2016). In other words, by ensuring that each pregnant woman has her own midwife. It’s time we did something about making this the universal standard of care with the same level of enthusiasm that clinicians describe for fetal movement monitoring programs.

Dr Kirsten Small