Back pain may affect pregnant women especially during later stages of their pregnancy. The prevalence of back pain during pregnancy is 48 - 56%. In fact it is so common that in most cases this symptom is looked upon as a normal part of pregnancy.

Around a third of all pregnant women may get severe back pain that compromises their ability to work in gainful employment during pregnancy and also interferes with their activities of daily living. Furthermore, back pain occurs at night in over one-third of pregnant women, contributing significantly to insomnia.

Pregnancy related back pain and risk factors

• Pregnancy-related back pain is commonly seen in women who have a history of previous episodes of back pain.
• The pain is usually most intense from the 12th week of pregnancy till 28th week and usually declines in intensity after that.
• Women with twin pregnancies or in later pregnancies (after the first pregnancy) may be more at risk of back pain. 
• Pregnancy related back pain may also be related to long hours of work and bad posture. Even bad shoes and heels and long hours of standing can contribute to back pain in a pregnant women.
• Furthermore Hispanic women have a proportionally lower instance of back pain in pregnancy than Caucasian women. 
• Younger age is also a risk factor, possibly due to higher sensitivity to hormonal   changes  induced by relaxin  and estrogens,  or  to more  pronounced collagen laxity
• Higher weight (obesity and overweight mothers) and those with a short stature are at higher risk of back pain
• Women who have had pain during pregnancy are also more likely to suffer from back pain after childbirth.

Mechanism of back pain during pregnancy

A normal pregnancy brings about several physiological changes in the body. These include mechanical and structural changes to the spine and hips to facilitate pregnancy and childbirth. Changes also include posture, gait (the nature of walk) and total body water content. There are hormonal changes and engorgement of blood vessels around the spine (epidural blood vessels).

The main change in posture is increased forward convexity of the spine (called lumbar lordosis). Most of the weight is thus concentrated low in the pelvis with a protruding abdomen. This leads to low back pain. This also causes a tendency to fall forwards.

Increased total body water means there is collection of fluids in the connective tissues around the vertebral column and pelvis. This increases the laxity around these joints. This fluid retention is also aggravated by hormonal changes of pregnancy. There is a hormone relaxin released during pregnancy. It  softens  the  ligaments around the pelvic joints  and cervix,  possibly by  enhancing fluid  retention  in  these  tissues and this helps in easy childbirth.

Treatment and prevention of back pain during pregnancy

• Patient education – This is vital. Maintenance of good posture, good methods of rising from sitting or lying position, prevention of awkward lifting etc. should be emphasized.  Patient is advised to stop smoking as this aggravates back pain.
• Physiotherapy – Physiotherapy in the third trimester may help ease back pain. Other physical treatments include mechanical support for the back for example a wedge shaped pillow for support (Ozzlo pillow), a belt or pelvic girdle etc.
• Labor pain can be managed appropriately to prevent back pain after childbirth.