INTRODUCTION

Low back pain is an important and commonly occurring public health problem with high impact to the person, family, and society. Prevalence figures of low back pain vary considerably across studies because of various factors, including case definition. In a prospective Danish study 40% of women, 25–34 years of age, reported low back pain during 1 year with a point prevalence of 20%, regardless of the degree of pain intensity or disability.¹ When disability of low back pain was taken into consideration, in a Canadian study, 50% of the population had experienced low-intensity/low-disability low back pain (including the sacral area) and 10% had experienced high disability low back pain in the previous 6 months, with a small age variation. Interestingly, women experienced almost twice the rate of high-disability low back pain compared with men.²

EPIDEMIOLOGY

In comparison to the 1-year prevalence of back pain among women from the general population, a reported 9-month prevalence rate of back pain during pregnancy, regardless of its onset, on average about 55% (range, 35.5–89.8%) has been reported.^3–16 The 9-month prevalence rate of back pain during pregnancy varies substantially among different studies with a mean prevalence rate within retrospective studies of 54% (range, 36–90%),^{3,5,6,8,9,11,13,15} and in prospective studies 58% (range, 49–88%) (Table 122.1).^{4,7,10,12,14,16} A true difference in prevalence of back pain between pregnant and nonpregnant women is strengthened by data from an Australian study where the odds ratio of having low back pain in pregnancy was 3.5 times higher than that of nonpregnant women.¹² Thus, it appears that back pain is more common during pregnancy than in the nonpregnant state or in men.

When back pain with onset during current pregnancy was considered, prevalence rates of between 61%⁷ and 88%¹⁴ was observed. The onset of back pain during pregnancy was fairly evenly distributed over the pregnancy period in most studies.^{5,7,8,13–15} The obvious conclusion derived from this information is that most women develop pregnancy-related back pain long before the commencement of abdominal enlargement or postural alterations. Among women developing back pain during pregnancy about 16% had reported a new location of back pain during the first 12 gestational weeks, 67% at 24th gestational week, and 93% at week 36. Thus, the largest proportion of pregnant women were experiencing new low back pain before their fifth month of pregnancy and a smaller proportion of pregnant women develop low back pain during the major growth period of the fetus.

Among women with back pain with onset during pregnancy, sacral pain is by far the most common location, reported by about 50% of women, followed in order by lumbosacral, lumbar, and thoracic pain. Cervical axial pain rarely manifests during pregnancy.^7,10 This is in contrast to pregnant women with back pain with onset prior to pregnancy when the lumbar and thoracic pain were the most common.⁷ Nearly every second women (45.5% and 46.8%) with pregnancy-related low back pain experiences symptoms that refer to the buttocks and thighs, occasionally down the legs,^5,6 but only rarely reaching the feet.⁵ True sciatica with pain below the knee was found in only 1%.¹⁰ Regardless of the symptom location in the lower extremity, a duration of 1–3 months is common. However, 5–10% of women report pain duration in pregnancy of more than 5 months where sacral pain is dominating.^4,7

Pain intensity among women with onset of back pain during pregnancy significantly increased over the duration of pregnancy. This is reflected by the duration of pain and not simply an increase during the later stages of pregnancy. This means that the longer the duration of back pain related to pregnancy the higher the reported pain intensity. In addition, there is a significant indirect correlation between pain intensity and age in several studies. Younger women reported higher pain scores than older women.^3,7,17

Among women with back pain during pregnancy the intensity of pain varied during the day and between days. One study showed that 16% of the pregnant women suffered from pain hourly, 66% daily, and 18% weekly.⁵ Among women with daily back pain, one-third reported increased pain toward the end of the day and one-third experienced increased pain during the night.^5,8 In the study by Mantle et al., nearly half of the women reported most troublesome backache in the morning.⁸ An explanation of this variation of back pain intensity could be that the intensity of back pain emerges over time during or after strain applied to the spine from various workloads, and then pain is relieved following rest. The specific load on the back initiates pain in susceptible women, leading to the greatest pain intensity later in the day, at night,^5,6,13 or the following morning.⁸ Back pain may result in an impaired sleep pattern as is demonstrated by decreased periods of rapid eye movement sleep.¹⁸ About one-third¹⁹ of pregnant women arose at night because of a backache, experiencing even more severe pain than during the day.⁶

Pregnancy-related back pain has a great impact on women, particularly those suffering from high-intensity pain when compared to pregnant women without pain at all. In prospective studies, about 30–35% of women with back pain describe the pain as a severe problem compromising normal, everyday life.^7,10 They preferentially describe difficulty with heavy physical work, heavy lifting, running, or physical exercise. They can also experience trouble with walking, sitting for longer than a few minutes, carrying a bag, or activities that require slight forward flexion while in the standing position (such as making the bed). This indicates that back pain during pregnancy causes restricted physical activity over and above that caused by pregnancy itself.⁷ The impact of pregnancy-related back pain is also highlighted by the fact that among previously pregnant women, one of five from the general population, as well as among women with scoliosis, refrain from becoming pregnant again due to fear of developing back pain during pregnancy.^20,21

Back pain related to pregnancy appears to be a global problem that occurs in developed as well as developing countries. High prevalence rates of back pain during pregnancy have been reported in Europe, America, Australia, China, including the mountainous region of Taiwan and Africa’s rural areas as well as among upper-class women in Nigeria.^{6,7,11–13,22,23}

Back pain during pregnancy has been reported from different ethnic groups.^5,6,7,9,