Introduction

Leg cramps (LCS) is a common musculoskeletal condition that is characterised by involuntary painful contractions of the leg muscles including the calf, hamstrings or foot muscles that occur suddenly at night and maybe episodic (Allen & Kirby, 2012). LCs are relieved by forceful stretching of the muscles affected, but the pain may linger on to the following day (Hensley, 2009). About 7 to 20% of LCs can happen during daytime only or either day or night (Monderer, Wu, & Thorpy, 2010; Naylor & Young, 1994). Benign LCs usually occur unilaterally, and during sleep (Hensley, 2009).

The prevalence of LC in the non-pregnant population varied according to demographics and is more common in the elderly. The prevalence of LC in the general adult population was reported as 37% while in the elderly group was 54% (Naylor et al., 1994). A study among the elderly participants in a UK population study reported that about 50% had experienced leg cramps (Abdulla, Jones, & Pearce, 1999).

The prevalence of LCs in pregnancy ranges from 18.2% to 75%. The lowest prevalence was in Australia while the highest prevalence was in Turkey (Hall et al., 2016; Kesikburun et al., 2018). Pregnant mothers in their second or third trimesters are more affected (Hensley, 2009; Ramachandra, Maiya, Kumar, & Kamath, 2015). It was previously postulated to be caused by metabolic or electrolyte imbalances such as deficiencies in magnesium, calcium, vitamin B12, folate, or iron (Supakatisant & Phupong, 2015; Zhou, West, Zhang, Xu, & Li, 2015).

Another mechanism that could lead to increased frequencies toward the later stages of pregnancy is fluid retention leading to distortion of the neuromuscular junction, weight gain, as well as joint laxity (Hensley, 2009; Miller & Layzer, 2005). This would later lead to the impaired blood supply to lower body organs, and increased pressure on leg muscles during pregnancy. This phenomenon will subside after pregnancy. Nonetheless, not all leg cramps occurring in pregnancy are benign and may need further assessment to rule out other conditions (Hensley, 2009). Differential diagnoses consist of deep vein thrombosis (DVT), post-DVT phlebitic syndrome or co-exist with sleep-related movement disorders such as restless legs syndrome, in which treatments are established. Even though LCs are common in pregnancy, its degree of impact on pregnant mothers is varied. This is because many of them had only brief episodes of LCs, but a substantial of others may experience severe pain that limits their daily activities (Allen et al., 2012).

When associated with sleep disturbance and/or sleep disorders, LCs could stand out as a concomitant risk factor for developing prolonged labour, thus affecting the mode of delivery. In an observational study among 131 pregnant women, it was shown that pregnant women who slept less than six hours per night and those with a severe sleep problem were, respectively, 4.5 times and 5.2 times more likely to undergo a caesarean delivery (Lee & Gay, 2004). If maternal's sleep quality is disturbed, LCs may co-exist to cause some impact on pregnancy outcomes such as increased risks of pregnancy-induced hypertension, pre-eclampsia, gestational diabetes, and depression (Palagini et al., 2014). Consequently, this could lead to prolonged labour, increased caesarean rates and prematurity (Lee et al., 2004; Palagini et al., 2014). If LCs are severe enough to cause sleep problems, they can be linked to anxiety and depression, leading to increased cytokines levels. As a result, this causes an increased risk of early labour with possible fetal asphyxia and postpartum haemorrhage (Dayan et al., 2002; Rondo et al., 2003). Other co-morbidities that LCs have been associated with especially when occurring at night are female sex, leg claudication, angina, arthritis, peripheral neuropathy, peripheral vascular disease and certain medications like statins, diuretics and long-acting beta-blockers (Grandner & Winkelman, 2017).

A Cochrane systematic review on interventions for LCs in pregnancy using magnesium, calcium or vitamin B12 supplements showed inconclusive evidence of their effectiveness (Zhou et al., 2015). A randomized control trial revealed that calcium with vitamin D, or vitamin D alone did not help in reducing the frequency, duration and pain intensity of LC in pregnancy (Mirghafourvand, Mansouri, Charandabi, & Najafi, 2017). Non-pharmacological treatment such as leg stretchers or massage also showed limited evidence in treating LCs. How pregnant mothers usually manage their symptoms are also lacking in the literature.

A systematic review showed that pregnant mothers in developed countries had lower QoL due to common symptoms of pregnancy (Lagadec et al., 2018). In pregnant mothers having LCs, it is anticipated that their QoL will be affected due to physical discomfort. Up to now, studies that examine the association of LCs in pregnancy with QoL in developing countries, especially South-East Asia, are few. Taking into account the complications LCs can be related to. This study aimed to explore its magnitude, characteristics and its association with QoL among pregnant mothers who were in their second or third trimesters. We hypothesised that the presence of LCs in pregnancy would reduce the QoL of pregnant mothers. We hope the findings of this study could provide information about the importance of detecting LCs in pregnancy as this condition is commonly underdiagnosed in clinical consultations.

Methodology

The cross-sectional study was carried out at a suburban government health clinic in the Hulu Langat district, Selangor between March and April 2018. The inclusion criteria for this study were pregnant mothers in the second or third trimester, aged 18 years old and above. Those who were illiterate in both Bahasa Malaysia and English or had an acute problem during their visit were excluded. The sample size was calculated using the Epi Info^TM STAT CALC. To answer the primary objective of the study, 112 pregnant mothers were required based on the expected frequency of LCs of 20% (Hall et al., 2016) from a finite pregnant population of 3000, a margin of error of 7.5%, a confidence level of 95%. This calculation had included consideration of 20% non-responders. Overall, 130 pregnant mothers were conveniently approached, whereby 114 met the inclusion criteria and consented to participate in the study.

Study tools

This study used bilingual (Bahasa Malaysia and English) self-administered questionnaire that consists of three sections assessing: a) socio-demographic and pregnancy clinical data (b) leg cramps (7 items), c) quality of life using the SF-12v2 questionnaire (12 items).

Pregnancy clinical data

This section looked at parity, gestational age, and booking BMI. Presence of major medical problems encountered in pregnancy such as diabetes, hypertension, anaemia or kidney problems including urinary tract infections, were also determined to identify confounding factors.

Leg cramps questionnaire

The section that assessed presence of LCs and their characteristics were developed in dual languages based on literature reviews (Blyton, Chuter, & Burns, 2012; Hallegraeff, Greef, Krijnen, & Schans, 2017) and discussions with an expert panel comprising of two Family Medicine Specialists and a specialist in Obstetrics and Gynaecology for content validity. Presence of leg cramps was assessed through a question: "Have you ever experienced leg cramps during this current pregnancy?" For those who answered "Yes", the descriptions of leg cramps were explored through six items: timing of leg cramps (usually during asleep or awake), the part affected (calf, foot, others), average duration, frequency, pain score and next-day soreness. These data were individually analysed and reported descriptively. The developed questionnaire was subjected to a pre-testing and face validity involving ten pregnant mothers from different socio-demographic backgrounds. Later, it had been piloted in a small group of pregnant women to assess the clarity and comprehensibility of the items. Subsequently, minor changes were made to improve the clarity of the final version of the questionnaire.

Quality of life questionnaire (SF-12v2)

Permission to use the SF-12v2 was obtained from the copyright holders (Mapi Research Trust and Quality Metric). The respondents' physical and mental well-being during the last four weeks were assessed. It is the shorter version of the SF-36 questionnaire comprising of 12 items, with a completion time of two to three minutes. There are eight subdomains including physical functioning (PF), role physical (RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), role emotional (RE) and mental health (MH). These subdomains can be summarised into the Physical Component Summary (PCS) and Mental Component Summary (MCS). The Quality Metric Health Outcomes Scoring Software 5.0 was used to calculate the scores of the main domains (PCS and MCS) and the eight subdomains. The mean score of the PCS and MCS domains ranged from 0 (the worst health) to 100 (the best health). The Cronbach alpha of the English-version of SF-12v2 were 0.89 for the PCS-12 and 0.86 for the MCS-12. The Bahasa Malaysia version of SF-12v2 was validated among Malaysian postpartum mothers in Kelantan that showed a Cronbach's alpha of 0.749 for PCS-12 and 0.701 for MCS-12 (Noor & Aziz, 2014). Due to widespread use, having good reliability and validity, availability in both Malay and English language, and shorter completion time (with the same coverage of health domains as SF-36), the SF-12 was chosen for this study.

Study flow

Respondent recruitment was done once a week on allocated research day (Tuesday) for a duration of 1 month (March to April 2018). Patients' case notes were accessed to clarify parity and BMI (booking and current) and medical illness. Participants who were found to have poor QoL were called for further assessment and intervention. The study flow is shown in Figure 1.

Data analysis

Statistical analysis was performed using the IBM SPSS® version 23.0. Descriptive analysis of all variables was done and presented as number (n) and percentage (%), mean and standard deviation (SD) or median and interquartile range (IQR). Bivariate analysis was performed using the chi-square test or Fisher's Exact test to look for any association between categorical variables. Non-parametric Mann-Whitney U test was used to examine the association between a categorical variable and numerical variable where the data was not normally distributed. Parametric independent t-test was used to look at the association between a categorical variable and numerical variable where the data was normally distributed. Statistical significance was at a p-value of less than 0.05.

Results and Discussion

Of the 114 pregnant mothers who met the study criteria and consented, 99 respondents completed the questionnaire. The response rate was 96.5%. The characteristics of the respondents are shown in Table 1.

As highlighted in Table 2, more than a third of pregnant mothers ever experienced LCs in this current pregnancy (71.7%), which mostly occurred during their sleep (80.3%). About half (50.7%) of them had LCs once to twice a week. LCs were significantly associated with gestational age (p = 0.001) and booking BMI (p = 0.022) as shown by Table 3. Among the other socio-demographics, pregnancy data and co-morbidities assessed, none were significantly associated with LCs.

The mean score for the physical component summary (PCS) of QoL was 45.5 (SD 6.4) [the possible range of the total score was between 0 and 100]. About 72% of the pregnant mothers had lower scores than the average of 50. The mean score for the mental component summary (MCS) was 51.8 (SD 7.91) and 58.6% of the pregnant mothers had scores above the average of 50. There was no significant association between the presence of LCs and any QoL components (p = 0.675 for PCS and p = 0.118 for MCS), as shown in Table 4.

This study can be considered as one of the pioneer studies, specifically focusing on LCs among pregnant mothers in Malaysia. In our study, only pregnant mothers in their second or third trimester were included because LCs were previously found to be more common in the later trimesters of pregnancy. A study in India showed that LCs were more common in the second and third trimester (Ramachandra et al., 2015). The statistically significant association between gestational age and LCs was demonstrated in our study as well, demonstrating the similarity of findings in Asian backgrounds. Those with LCs were in their later trimester [median of gestational age: 31 (IQR 10) weeks] compared to those without LC [median gestational age: 27 (IQR 11) weeks]. It is postulated to be due to increased fluid retention or joint laxity toward the third trimester (Miller et al., 2005).

Generally, the respondents in this study were well pregnant mothers, as most of them had no co-morbid illness. Only 18.2% of them had anaemia, 1% had reported kidney disease (later clarified to be a urinary tract infection), 10.1% had diabetes mellitus or gestational diabetes and 3% had hypertension. Although all these medical problems have been associated with LCs in previous literature, (Hensley, 2009; Miller et al., 2005) but due to the small magnitude of each illness in this study, their associations with LCs were not statistically significant. Alternatively, 30% of the general population in a study reported of having night time LCs with higher frequency (more than five per month). They were significantly associated with co-morbidities like hypertension, diabetes, heart failure, angina, depression and respiratory diseases (Grandner et al., 2017). Furthermore, LCs associated with co-morbidities are usually identified as secondary causes, whilst benign LCs in pregnancy are thought to be either idiopathic, metabolic or physiological, which explains the low magnitude of LC co-morbidities in this study.

Many of our pregnant mothers (82.8%) were either overweight or obese at booking (BMI > 23 kg/m²). This finding was higher than a local study by Lim et al., 2013 which found that 62.3% of the pregnant population in their study had BMI above 23 kg/m². The average booking BMI of the pregnant mothers in this study was 24.6 kg/m². Studies observing LCs in pregnancy and the association with BMI are still lacking, especially in the South-East Asian region. Our study highlights that LCs may be more common among pregnant mothers who were overweight or obese compared to those with normal weight and the association between BMI and LCs were statistically significant. A similar significant association was found among the non-pregnant general population (Grandner et al., 2017). Since overweight and obesity appear to be common among pregnant women, it highlights the importance of healthcare providers to manage the pre-pregnancy weight of the reproductive women before they conceive. Reduction in pre-pregnancy weight might help them to reduce their chances of having LCs during pregnancy. However, further studies are required to prove the effect of reduction in the pre-pregnancy weight on the occurrence of LCs as this study did not examine this effect.

In our study, a large proportion of pregnant women (71.7%) experienced LCs during this current pregnancy. This proportion was slightly lower than the reported study in Turkey (75%) (Kesikburun et al., 2018). Other international studies stated the following prevalences of LCs, i.e. Australia (18.2%), Iran (54.5%), and India (64.6%). A majority of the pregnant mothers in this study (80.3%) sustained LCs mainly at night time and only 19.7% had it during the day time. A similar occurrence of LCs was observed in a study whereby 88% of the respondents had LC at night only and the remaining 12% had LC both night and day symptoms (Dahle, Berg, Hammar, Hurtig, & Larsson, 1995). This is not surprising as the nature of benign LCs mostly does occur at night time. Further evaluation is needed to assess whether the sleep quality of these pregnant mothers is affected to assess the risk of complications in labour outcomes, mode of delivery and fetal compromise.

Even though LCs were common among the pregnant mothers in this study, the description of LCs in terms of its frequency, duration and severity of pain suggests that LCs might be tolerable by them. They appeared to have less frequent LCs compared to the pregnant women in two randomised control trials (Dahle et al., 1995; Mirghafourvand et al., 2017). In our study, about half of the pregnant mothers had once to twice LCs in a week. However, before starting the intervention, about 80% of the pregnant mothers had three or more LCs in a week (Dahle et al., 1995), whereas the pregnant women in another study reported an average of 5 to 6 LCs per week (Mirghafourvand et al., 2017). Nevertheless, the frequency of LCs in the current study was more than the general Americans; which reported that the majority of their participants had LCs less than once a week (Naylor et al., 1994).

The average duration of LCs described by our pregnant mothers was two minutes and 63.4% of them had moderately painful LCs based on the visual analogue scale (VAS). A similar description of LCs was found in a previous study; in which the duration of the LCs before the intervention was between 1.6 and 4.3 minutes and the pain score based on VAS was between 4.9 and 5.1 indicating moderate pain (Mirghafourvand et al., 2017). In addition, 26.7% of our pregnant mothers suffered severe LCs with VAS of 7 or more; thus, their LCs should not be disregarded. This suggests that although LCs may be assumed as benign in most cases, it is still worthwhile to be elicited during history taking, especially in their second to third trimesters. This is because some pregnant mothers may not reveal their LC symptoms to healthcare providers without being prompted. Furthermore, it is important to ensure that there are no secondary causes or concomitant conditions with LCs in pregnancy, such as DVT, or sleep disorders that require urgent attention or proper treatment.

The physical impacts of LCs on the pregnant mothers in this study appears to be mild as most of them (43.6%) had never or rarely experienced next-day soreness. Next-day soreness only occurred 'sometimes' for many of them (43.7%). This finding is contrary to previous findings, whereby 40% of their pregnant women reported to 'always' have next-day soreness (Dahle et al., 1995). About 34.3% of them experienced the soreness in some of the time and 25.7% of them denied having the next-day symptoms. However, 12.7% of the pregnant mothers in this study were substantially affected by the next-day soreness and they may need treatment to alleviate LC.

Majority of the pregnant mothers (71.7%) experienced below-average physical well-being, but many had above average mental well-being (58.6%). A study was carried out comparing the QoL pregnant mothers of all trimesters, in the urban and rural areas in Islamabad, Pakistan, using the SF-12 questionnaire (Naseem et al., 2011). It was found that the mean PCS and MCS scores for the urban group were 49.87 (SD 22.27) and 58.07 (SD 15.07), respectively. In this present study, the mean PCS and MCS scores were 45.4 (SD 6.4) and 51.8 (SD 7.9) sequentially. Considering possible similarities of sub-urban and urban backgrounds, the findings of this study were consistent with findings from (Naseem et al., 2011); where the mean MCS score was relatively higher than the mean PCS score. The pregnant mothers in this study can be assumed to have reasonably good mental health capacity to endure the physical discomforts of their pregnancy, including LCs. To add to that, the presence of LCs in this study was insignificantly associated with the QoL of pregnant mothers. Because LCs in this study were perceived as tolerable, it reflects why their QoL was not affected. This would conform with some theories of psychological empowerment of pain management. However, caution must be observed to assess whether these pregnant mothers would go on to perceive pain similarly throughout the whole pregnancy. In serial consultations, it is important to evaluate whether the LC symptoms have worsened which could jeopardize their QoL.

Conclusions

Leg cramps (LCs) appear to be common in pregnancy as the majority of pregnant mothers in this study did experience LCs which were brief, mild and infrequent. An insignificant association between LCs with QoL was found in this study, contrary to our hypothesis. Despite this, LCs should not be disregarded, as a subgroup of pregnant mothers experienced severe LCs with next-day soreness.

Acknowledgement

We would like to express our gratitude to Professor Dr Khairani Binti Omar, from the Family Medicine Department of Management and Science University (MSU), for sharing her wisdom throughout this research. Our extended gratitude to the Director-General of Health, Ministry of Health of Malaysia, for granting permission for the execution of this research. The study protocol also gained approval from the Ethics committee of the National University of Malaysia (UKM) and the National Medical Research Register of Malaysia (NMRR).

Conflict of Interest

The authors declare that they have no conflict of interest for this study.

Funding Support

The authors declare that they have no funding support for this study.