This is the third, and final, post in a series about the risk of CTG use. You can find the first post here and the second one here. This post looks at the possibility that CTG use might cause harm to the baby, while the two previous posts have examined the risk to birthing women.
Dominant cultural attitudes in high-income countries view infants as precious, pure, and vulnerable (Lupton, 2013a), and good motherhood is regarded as making personal sacrifices in order to protect their children (Lupton, 2013b). If women believed that CTG monitoring is of benefit for the baby, many women might make an informed decision favouring the use of CTG monitoring in spite of their personal risk. On the other hand, if the baby might be put at risk, women would be unlikely to make the same choice. It is therefore important to examine what the evidence says about the risk to the baby.
I’m going to summarise the evidence in three different categories. First, I’ll look at evidence from randomised controlled trials that poor perinatal outcomes are higher when CTGs are used. Next, I’ll look at the small body of evidence relating to direct risks to the fetus from the use of internal fetal monitoring technology. Finally, I’ll examine evidence which shows that babies born by surgical birth are at higher risk for poorer health outcomes.
RCT Evidence: Are babies worse off when CTG monitoring is used rather than IA?
I have previously discussed the evidence produced by Haverkamp and colleagues in 1976 that raised the possibility that the use of intrapartum CTG monitoring might increase the incidence of fetal heart rate abnormalities. Turning to the Cochrane review which synthesises the findings of all the randomised controlled trials comparing CTG monitoring with IA during labour (Alfirevic et al., 2017) we can see the following:
- The rate of cerebral palsy more than doubled (risk ratio of 2.54) when CTG monitoring rather than IA was used for high risk women (specifically those in premature labour). This reached statistical significance.
- Across all studies the risk of neurodevelopment delay at 1 year of age was almost four times higher when CTG monitoring was used (but didn’t achieve statistical significance).
- No improvement in perinatal mortality in either the low- or high-risk groups of women.
When we look at antenatal CTG use in women considered to be at risk (Grivell et al., 2015) we find a doubling of perinatal mortality (which just fails to reach statistical significance). Collectively, these findings put the idea that CTG monitoring is harmless to the fetus on shaky grounds.
Damaging the baby with internal fetal monitoring technology
Early CTG researchers noted cases of scalp trauma (lacerations, haematoma formation) or infection (scalp abscess) occurring when a fetal electrode was used (Koh et al., 1975; Roux et al., 1970). The Alfirevic review (2017) found a threefold increase in scalp trauma and or infection when CTG monitoring was used. A fetal death was reported as a consequence of injury from a fetal electrode to a prolapsed umbilical cord (de Leeuw et al., 2002). Ascertaining the incidence of such events is challenging, as they have generally reported as individual case studies.
Concerns have been raised that the use of a fetal electrode might increase the perinatal transmission of group B streptococcus, human immunodeficiency virus, hepatitis B and C, and herpes (Murray, 2002). Koszalka and team (1982) examined the effects on neonatal infection when women were randomised to either IA or CTG monitoring with a fetal electrode. While they found no difference in the overall rates of neonatal infection, a much higher incidence of meningitis was noted among infants exposed to both a fetal electrode and to scalp blood sampling (7% of this group). Gill et al. (1997) found a significant increase in neonatal deaths from early onset group B streptococcal sepsis when infants with bacteriological evidence of colonization had been monitored with a fetal electrode during labour.
From the available data, it appears that there is a small, difficult to quantify, risk of harm to the infant during intrapartum CTG monitoring when a fetal electrode used. While this risk can possibly be reduced through correct approaches to application and use of the electrode, screening of women for infectious diseases and giving prophylactic antibiotics, it can be avoided completely by not using CTG monitoring, or where this is in use, using external approaches to monitoring.
Risks of surgical birth
In part one of this series I reviewed the evidence which showed that intrapartum CTG use is associated with higher rates of caesarean and instrumental birth, and examined the consequences of this for birthing women. There are also consequences for infants. In the short-term, infants born by caesarean section during labour have higher rates of jaundice, feeding problems and hypothermia shortly after birth than those born vaginally (Peters et al., 2018). Caesarean born children also experience higher rates of health problems in later life. Conditions which have been linked to caesarean birth are:
- respiratory and other infections, eczema, metabolic disorder (Peters et al., 2018),
- obesity (Li et al., 2012),
- asthma (Huang et al., 2014),
- type 1 diabetes (Cardwell et al., 2008),
- systemic connective tissue disorders, juvenile arthritis, inflammatory bowel disease, leukaemia (Sevelsted et al., 2015)
- altered immune function (Cho & Norman, 2013),
- neurological morbidity (particularly autism and movement disorders) (Baumfeld et al., 2018), and
- underachievement at school (Polidano et al., 2017).
Infants who are born with the assistance of either vacuum extraction or forceps can experience trauma related to the use of instruments. Use of the vacuum extractor is associated with a particular form of haemorrhage occurring under the surface of the scalp (cephalohaematoma), and this risk is greater when the procedure has been performed for an abnormal fetal heart rate pattern rather than a prolonged second stage of labour (Salman et al., 2017). While uncommon (an incidence of 1 in 413 births), the use of obstetrical forceps can cause trauma to the infant’s eye (McAnena et al., 2015).
Some births are complicated by difficulty achieving the birth of the shoulders after the infant’s head has been born, a condition known as shoulder dystocia. Instrument assisted births increase the risk of this complication (in comparison with non-instrumental vaginal birth) (Asta et al., 2016) and are associated with an increased incidence of neurological injury of the infant as a consequence of shoulder dystocia (Brimacombe et al., 2008).
Mirroring the findings for caesarean birth, instrumental birth has been associated with a higher incidence of jaundice, feeding problems, and hypothermia in the short term (Peters et al., 2018) along with a number of long term poor health outcomes. These include higher rates of asthma in adolescence (Hancox et al., 2013; Keski-Nisula et al., 2009), and higher rates of eczema, metabolic disorder and respiratory infections (Peters et al., 2018) in comparison with children born without the use of instrumental assistance.
Non-maleficence (often illustrated by the Latin phrase primum non nocere, or first do no harm [Smith, 2005]) is a core ethical principle in health care, requiring clinicians to ensure that the benefits clearly outweigh the harms of any planned intervention. There is no doubt at all that there is limited benefit from the use of intrapartum CTG monitoring and clear evidence of harm. As clinicians in maternity care our discussions with women need to go well beyond “let’s just pop the monitor on to be on the safe side”. In order to begin having honest conversations with birthing women, we first need to start with honest conversations within our professions about the failure of CTG monitoring to delivery on its promises.
Alfirevic, Z., Devane, D., Gyte, G. M. L., & Cuthbert, A. (2017). Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database of Systematic Reviews, 2,(CD006066), 1-137. https://doi.org/10.1002/14651858.CD006066.pub3
Asta, A. D., Ghi, T., Pedrazzi, G., & Frusca, T. (2016, Sep 01). Does vacuum delivery carry a higher risk of shoulder dystocia? Review and meta-analysis of the literature. European Journal of Obstetrics, Gynecology, and Reproductive biology, 204, 62-68. https://doi.org/10.1016/j.ejogrb.2016.07.506
Baumfeld, Y., Sheiner, E., Wainstock, T., Segal, I., Sergienko, R., Landau, D., & Walfisch, A. (2018). Elective cesarean delivery at term and the long-term risk for neurological morbidity of the offspring. American Journal of Perinatology, 35(11), 1038-1043. https://doi.org/10.1055/s-0038-1637001
Brimacombe, M. M., Iffy, L. L., Apuzzio, J. J., Varadi, V. V., Nagy, B. B., Raju, V. V., & Portuondo, N. N. (2008). Shoulder dystocia related fetal neurological injuries: the predisposing roles of forceps and ventouse extractions. Archives of Gynecology and Obstetrics, 277(5), 415-422. https://doi.org/10.1007/s00404-007-0465-7
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