The Effect of Music Therapy on Labour Pain, Anxiety, and Analgesia

The Cambridge dictionary describes pain as a feeling of physical suffering caused by injury and illnesses. This physical suffering is a subjective, natural, and inevitable process associated with labour that is understandably, a most feared aspect of pregnancy for expectant mothers. A woman's birthing experience is influenced by her social environment and how she contextualizes the idea of pain as purposeful and productive versus threatening, the latter of which could result in a more negative pain response. Historically prior to the 18th century, natural methods were the only options for pain relief for women in labour. These included various breathing techniques and positioning, massage techniques and herbal mixtures. There is an increasing movement back to the historical practices of traditional and non- pharmacological pain relief during labour, and research in these techniques is needed to prove clinical effectiveness. According to the World Health Organisation (WHO) recommendations: intrapartum care for a positive childbirth experience- " Most women desire some form of pain relief during labour, and qualitative evidence indicates that relaxation techniques can reduce labour discomfort, relieve pain and enhance the maternal birth experience."

One of the most used pharmacological agents during labour is meperidine hydrochloride (Pethidine®) as it is readily available with a higher level of administrator comfort than other agents. Overuse of pharmacological interventions can lead to increased maternal and neonatal morbidity, reduced local supply of pharmacological agents and even financial strain on low resource institutions. Patients with a low pain threshold in early labour due to anxiety and fear may also request analgesia in the latent phase which can result in the inability to receive repeated doses early in the active phase due to dosing frequency guidelines. This can then result in maternal distress and poor labour outcomes when the additive effect of labour progression, results in more severe pain. Meperidine hydrochloride has been shown to offer variable pain control with a more sedation than analgesic effect, hence adjunctive therapy with music may prove beneficial for its potential additive analgesic effect. Meperidine hydrochloride's use has also been found to be associated with increased rate of augmentation in labour, increased operative deliveries, and adverse maternal effects such as nausea, vomiting and dizziness and also a linkage to neonatal respiratory depression \& APGAR scores \< 7 and acidosis [umbilical artery potential of Hydrogen (pH) \<7.12] have been noted.

The United Nation (UN) Global Strategy for Women's, Children's and Adolescents' Health seeks to ensure that not only do women survive childbirth complications if they arise, but also that they thrive and reach their full potential for health and life. To facilitate safe labour and childbirth, attention must be given to the management of the psychological and emotional needs of women. Anxiety of the labour process is frequently seen in mothers presenting for delivery. This is shown to be more common in primiparous women especially if they have not received antenatal counselling on what to expect in labour(9). Studies have shown that anxiety can stimulate the sympathetic nervous system, releasing excessive stress hormones such as cortisol and adrenaline contributing to dysfunctional uterine contractility and labour dystocia. Music therapy has been shown to be an effective, inexpensive, safe and non-invasive intervention for patients undergoing many non-obstetric procedures such as decreased pain and anxiety during bone marrow biopsy and aspiration and nasal bone fracture reduction as well as decreased anxiety and propofol (Diprivan®) consumption during colonoscopy/endoscopy.

With more women exploring the option of physiological birthing techniques ("Natural Birthing Techniques"), an approach to labour and birth that normalizes the strength and physiology of the woman and foetus and refrains from external intervention unless there is potential compromise to mother or foetus, music therapy may offer a natural alternative to pharmacological approaches to pain relief that are the standard of care in may labour and delivery suites.

Music can have a direct impact on the perception of pain by activating the gate-control theory of pain which attacks both cognitive and physiological factors associated with pain. The gate theory works on the idea that there is a gateway in the dorsal horn of the spinal cord that manages the perception of pain via opening and closing of this gate. Pain sensation is carried via small neural fibres that pass this gate in route to the brain for interpretation. Music can close this gateway by stimulating a large number of neurological fibres some of which would have been activated for a pain response if available, and hence no transmission of pain sensation in response to stimulation. Music can also serve as a distraction mechanism improving general mood and hence decreasing negative pain perception.

Music during labour is perceived by the right hemisphere of the brain and can result in the release of endorphins which provide analgesia by binding to opioid receptors at pre and post synaptic nerve terminals. This binding results in the inhibition of substance P an important protein involved in the transmission of pain. Studies show that decreased levels of serum cortisol and the release of neural system of reward hormones such as dopamine is linked to the anxiety reducing effect of music therapy.

In a study performed by Buglione et al., pain level during active phase of labour was 8.8 ± 0.9 in music group and, 9.8 ± 0.3 in control group [Mean Difference (MD) - 1.00 point, 95%, Chloride (Cl) - 1.48 to - 0.52; P \<0.01]. Music during labour and delivery was also associated with decreased pain 1h postpartum as well as decreased anxiety levels during the active phase, second stage and 1hour postpartum. This study was however studied in a small population of 30 Italian women; hence generalizability of findings is uncertain. A meta-analysis and systematic review of studies published between 2003 and June 2018 showed significant differences in Visual Analog pain scale (VAS) scores in favour of music therapy in the intensity of latent phase of labour pain (MD: -0.73; 95% Cl -0.99, -0.48); in the active phase (MD: -0.68; 95% Cl -0.92, -0.44) in its entirety or during the first phase (MD: -1.71; 95% Cl -2.65, -0.77) and second hour postintervention (MD: -2.90; 95% Cl -3.79, -2.01). In terms of anxiety, Santiváñez-Acosta et al evaluated three studies which revealed significant differences in anxiety level in the latent phase (MD: -0.74; 95% Cl -1.00, -0.48) and active phase of labour (MD: -0.76; 95% Cl -0.88, -0.64).