For many years, healthcare providers worked to manage labour actively and safely, with the main aim of shortening the duration of labour. There has been an extensive increase over the last two decades in using a multiplicity of labour techniques to improve outcomes for both mothers and babies [1]. Despite these, the concept of normality in labour in terms of progression and duration is not universal [2]. However, in clinical practice, it is crucial to differentiate normal from abnormal so that women and care givers can agree on what to anticipate and when labour interventions are appropriate [2].

Labour is a process that is subdivided into 3 stages. When labour starts, the first stage begins, and it ends when the cervical dilatation and effacement are complete. The second stage starts with full cervical dilatation and ends with the birth of the fetus. After the baby is born, the third stage commences, and it concludes with delivery of the placenta and membranes [3].

The duration of the first stage of labour takes about 12 - 16 hours for nulliparous women and 8 - 12 hours for multiparous women [4]. If the first stage of labour lasts more than 16 hours for a nulliparous woman and more than 12 hours for a multiparous woman, it is deemed prolonged [4]. Evidence shows that one-third of first-time mothers experience a delay during the initial phase of labour [5].

Prolonged labour often ends up in immense agony for the parturient and adverse outcomes for the fetus. Prolonged labour can result in maternal and perinatal complications. Maternal complications include fatigue, electrolyte imbalance, hypoglycaemia, and obstructed labour and its sequalae, including obstetric fistula, ruptured uterus, and primary postpartum haemorrhage. Fetal distress, birth asphyxia, increased risk of newborn resuscitation and intensive care unit hospitalization, hypoxic ischaemic encephalopathy, and cerebral palsy are some of the perinatal complications [6].

The strategies for shortening the duration of labour have been an area of continuous research. The active management of labour theory, which was initially presented in Dublin by O’Driscoll et al. in an effort to reduce the duration of labour, calls for the obstetric care provider to actively affect the course of labour as opposed to passive observation [7]. Many support active management of labour since it has been demonstrated to reduce the rate of caesarean sections, duration of labour, and prevent prolonged labour, without having a negative impact on the mother or the fetus [7].

The key factors guiding the course of labour are cervical dilation, uterine contractions, and the descent of the presenting part [8]-[10]. However, inhibitory compulsions in the form of spasms may prevent cervical dilatation even in the case of adequate uterine contractions, resulting in prolonged labour. In such cases, the cervix may dilate with the aid of antispasmodics. Several randomized clinical trials have reported the use of antispasmodics to overcome cervical spasms [11].

Several drugs have been used to achieve effective dilatation of the internal cervical os, majority of which were observed to have adverse effects on mother and fetus [12]. Atropine is one such medication that was safe but had unpleasant side effects, such as heart problems, visual abnormalities, suppression of perspiration and salivary secretions [6]. This resulted in the production and use of many quaternary ammonium scopolamine derivatives [6].

Hyoscine-N-butyl bromide (scopolamine) is a derivative of quaternary ammonium that has been proposed to reduce the duration of labour [8][13]. It is a semi-synthetic derivative of scopolamine and is a member of the parasympatheticolytic medication class. Hyoscine-N-butyl bromide does not cross the blood brain barrier unlike atropine; consequently, at therapeutic doses, it does not cause the central effects of atropine [1].

Primarily, by reducing spasms in the smooth muscles of gastrointestinal tract, biliary system, urinary tract, and cervico-uterine plexus, hyoscine-N-butyl bromide aids in cervical dilatation. Intraneural parasympathetic ganglia in the abdominal organs and cholinergic transmission at synapses in pelvic and abdominal parasympathetic ganglia are both inhibited by this substance [14]-[16].

Hyoscine-N-butyl bromide has been used in obstetric practice in few countries to accelerate the first stage of labour. However, majority of the evidence demonstrating its efficacy has been anecdotal, and the mechanism that operates in the context of labour has not yet been evaluated [17].

The socio-demographic characteristics are shown in Table 1. Most were aged 19 - 30 years, accounting for 67.2% of the HBB group and 71.9% of placebo group, with a mean age of 27.5 ± 4.4 years in the HBB group and 27.7 ± 4.1 years in placebo group (p = 0.8). The mean gestational age was 39.4 ± 1.3 weeks for the HBB group and 39.2 ± 1.4 weeks for the placebo group (p = 0.3). The HBB group had a mean cervical dilatation rate of 1.01 ± 0.1 cm/hour, whereas the placebo group showed a marginally higher rate of 1.03 ± 0.1 cm/hour (p = 0.4). This is shown in Table 2.

The fetal heart rate was similar between the groups, with means of 142.6 ± 7.7 bpm for the HBB group and 142.5 ± 7.3 bpm for the placebo group (p = 0.9). There was a significant difference in the fetal heart rate 30 minutes post-administration. The HBB group showed a slight increase to 143.4 ± 7.2 bpm, while the placebo group experienced a small decrease to 140.6 ± 7.9 bpm (p = 0.04), suggesting a potential effect of HBB on fetal heart rate. This is shown in Table 3.

Table 4 shows the mean duration of labour. Regarding the first stage, the HBB group had a mean duration of 295.1 ± 29.0 minutes, while the mean duration for the placebo group was 293.6 ± 29.5 minutes (p = 0.8). Thus, suggesting that HBB had little effect on the duration of the first stage. For the second stage of labour, the HBB group had a mean duration of 19.5 ± 5.1 minutes, compared to 19.5 ± 6.0 minutes in the placebo group (p = 1.0). When considering the duration of the first and second stages, the HBB group showed a slightly longer mean time (314.6 ± 29.3 minutes) compared to the placebo group (313.2 ± 30.0 minutes). However, this difference was not statistically significant (p = 0.8). The third stage of labour showed a trend towards a longer duration in the HBB group (4.5 ± 1.4 minutes) compared to the placebo group (4.0 ± 1.4 minutes). The total duration of labour was longer in the HBB group (319.0 ± 29.2 minutes) compared to the placebo group (317.1 ± 29.9 minutes), with no statistical significance (p = 0.7), suggesting that HBB did not significantly alter the overall duration of labour. The time from drug administration to delivery was similar in both groups. The HBB group had a mean interval of 5.1 ± 0.6 hours, while the placebo group was 5.1 ± 0.7 hours (p = 0.8).

Both groups showed a high rate of vaginal deliveries, with the HBB group having a slightly higher proportion (92.2%) compared to the placebo group (84.4%). Conversely, the rate of caesarean deliveries was lower in the HBB group (7.8%) than in the placebo group (15.6%). These differences were not statistically significant (p = 0.2). This is shown in Table 5.

The mean birth weight in the HBB group was 3.4 ± 0.4 kg, while in the placebo group it was 3.3 ± 0.4 kg (p = 0.6). Regarding APGAR scores, at 1 minute, the mean APGAR score for the HBB group was 7.3 ± 0.9, compared to 7.3 ± 1.0 for the placebo group (p = 0.6). Similarly, at 5 minutes, the HBB group showed a slightly higher mean score (8.6 ± 0.5) compared to the placebo group (8.5 ± 0.6), again, this difference was not statistically significant (p = 0.2). In the HBB group, 6.3% of newborns required NICU admission, compared to 10.9% in the placebo group (p = 0.3). In the HBB group, 50% of NICU admissions were due to Infants of diabetic mothers (IDM), while in the placebo group, 57.1% of admissions were due to birth asphyxia (p = 0.2). This is displayed in Table 6.

Table 7 compared the incidence of various side effects and complications between the HBB and placebo groups. The most notable finding was occurrence of dry mouth, which was reported by 9.4% of participants in the HBB group compared to 3.1% in the placebo group (p = 0.3). Nausea and vomiting were reported in both groups, with a slightly lower incidence in the HBB group (9.4%) compared to the placebo group (10.9%). However, this difference was not statistically significant (p = 1.0), indicating that HBB did not significantly increase the risk of these common symptoms during labour.

Table 1. Socio-demographic characteristics.

α = Mean ± SD; χ² = Chi-Square; t-test = Student t-test; µ = Fisher’s exact p.

Table 2. Mean rate of cervical dilatation between HBB and Placebo groups.

t-test = Student t-test.

Table 3. Comparison of vital signs between HBB and Placebo groups before and after drug administration.

*Statistically significant (p ≤ 0.05); t-test = Student t-test.

Table 4. Mean durations of the first, second and third stages of labour in the first stage of labour between the test and placebo group.

*Statistically significant (p ≤ 0.05); t-test = Student t-test.

Table 5. Mode of delivery.

*Statistically significant (p ≤ 0.05); χ² = Chi-Square; µ = Fisher’s exact p.

Table 6. Neonatal outcome.

*Statistically significant (p ≤ 0.05); t-test = Student t-test; µ = Fisher’s exact p.

Table 7. Maternal outcome.

Shortening the duration of labour is a key goal of intrapartum care, as it reduces pain, anxiety, and stress for mothers [16]. This, in turn, can greatly enhance their overall satisfaction with the childbirth experience. Furthermore, reducing the duration of labour can also decrease the need for medical interventions, leading to better outcomes for both mothers and babies [16].

In this study, the duration of the first stage of labour was comparable. This was consistent with the study by Barau [6], who also reported no statistical difference, but Aldahhan observed a significantly longer duration in the intervention arm [17].

However, the main distinction between the current study and that of Barau was that the former included women with cervical dilation of 5 cm, whereas the latter included women in spontaneous labour at term with a cervical dilatation of 4 to 5 cm. Furthermore, whereas our study only looked at nulliparous women, Barau included both nulliparous and multiparous women. Conflicting results from other studies suggested that HBB actually shortened the initial stage of labour, underscoring the need for more study to elucidate these differences [18]-[20]. One possible explanation for the discrepancy in the study by Ejikeme et al. was that a higher dose of 40 mg of HBB was used. This may be because it may be difficult to ascertain when the second stage of labour begins [21].

The placebo group showed a faster cervical dilation rate than the HBB group early on in labour. This is not consistent with those of previous studies that showed that HBB increased the rate of cervical dilatation [22][23]. The study by Kinyna et al. included both nulliparous and multiparous women, which might have accounted for this disparity. In the study by Akiseku et al. despite recruiting nulliparous women like the current study, it demonstrated a significant difference in the mean rate of cervical dilatation between the hyoscine group and the placebo group [23].

The total duration of labour, encompassing all three stages, was longer in the HBB group (319.0 ± 29.2 minutes) compared to the placebo group (317.1 ± 29.9 minutes). Although the HBB group had a slightly longer duration of labour, this variance was not statistically significant, suggesting that HBB did not significantly alter the overall duration of labour.

In terms of maternal side effects, this study showed that dry mouth was the most common side effect in the HBB group compared to the placebo group. It is particularly noteworthy that no participants in either group experienced cardiovascular symptoms. This is reassuring, as it suggests that HBB does not have significant cardiovascular effects, which is an important consideration for any medication used during labour. Hence, a single dose of 20 mg HBB given intravenously is relatively safe with minimal side effects to women in labour. This finding is similar to previous studies [8][20][23]-[25]. Aldahan et al. differed from our study, their study showed that the HBB group had significantly higher rates of maternal tachycardia [17].

Given that the increase in fetal heart rate was statistically significant, the use of HBB during labour may be associated with increased fetal risk. Despite this increase, the Apgar score did not change substantially from that of the control group. This is comparable to the findings by Aldahhan et al., who reported that fetal heart rate was considerably higher in cases than in controls [17].

High proportion of vaginal births was observed in both groups; indicating that HBB may encourage vaginal deliveries. Furthermore, Qahtani et al. [26] revealed that although the control group had a somewhat higher rate of instrumental delivery, the rate of caesarean births among women who had HBB was not notably greater. This is contrary to what was reported by Aldahhan et al. [17] who reported that the HBB group had a higher caesarean delivery rate, which contradicts our findings. This difference might be because HBB significantly reduced cervical dilatation rate in the test group.

Based on APGAR scores at one minute and five minutes, the groups did not significantly vary for neonatal outcomes. This implies that HBB does not have a deleterious effect on newborn well-being. The results of previous studies are comparable to this, where Apgar scores of newborns delivered to mothers in the two groups were similar, irrespective of the dosage of HBB used and their routes of administration [8][13][18]. These findings provide confidence in the safety profile of HBB as demonstrated in our study.

The duration of the active phase of labour in nulliparous women was unaffected by a single 20 mg dose of intravenous hyoscine butyl bromide. HBB did not cause significant maternal side effects, nor did it alter the feto-maternal outcomes. However, after administration, there was a significant increase in the fetal heart rate. Based on the findings of this study, the routine use of 20 mg IV HBB to shorten labour in nulliparous women is not supported, as there was no significant change in the duration of the active phase of labour.

The trial, which was the first in the study center, was used as a pilot for more extensive research. In addition, meticulous attention was paid to the recruitment of participants by adhering strictly to the inclusion criteria. Furthermore, since randomization was used, the possibility of selection bias was minimized. This study only included nulliparous women in labour with term pregnancies, the effect of increasing parity on reducing labour duration was excluded. The external validity was further enhanced by the use of an impartial assessor throughout the entire process.

It was a single center study with a small sample size, and a significant number of women were excluded, thus findings may not accurately reflect the general population. Another limitation was the unavoidable inter- and intra-observer error that could have occurred in assessing for cervical dilatation.

It is recommended that a larger multi-center study may be conducted to further evaluate the usefulness of HBB in shortening the duration of labour. This may be done by randomized controlled trials to evaluate the impact of higher or repeated doses of HBB. A dose of 40 mg or even two intravenous doses of 20 mg HBB spaced a few hours apart could be used instead. However, from the findings of this study, HBB did not shorten the active phase of the first stage of labour, and as such should not be recommended.

*Corresponding author.