We are living in the age of women’s health studies. Large groups of women are enrolled in several long-term studies around the world. For example, the Nurses Health Study I sponsored by the National Institutes of Health was started in 1976. The main reason for the study was to see if there were any long-term problems from using oral contraceptives. Since that time, the data has been analyzed for many other purposes.
A second study (Nurses Health Study II) was started in 1986 and expanded from the original research. Other large studies of men and women together also provide data on both genders that can be analyzed separately. For example, the Framingham Study has been used to understand heart disease.
Data from the Monitoring Project on Risk Factors for Chronic Diseases (MORGEN) in the Netherlands has been used to compare reproductive and hormonal factors with musculoskeletal pain in women. The focus was on chronic back and/or arm pain.
Researchers found that a history of past pregnancy was associated with an increased risk of musculoskeletal pain. Likewise early age (less than 20 years) at the time of the first pregnancy was linked with chronic low back pain (LBP) later.
Studies show about 10 per cent of women with chronic LBP report it started during pregnancy. The exact biologic mechanism is unknown. It’s likely that there are many factors, not just one. Stress on joints and ligaments, fatigue, and hormones designed to relax the soft tissues may all have a role.
It’s also possible the combination of hormonal factors and the work load of caring for young children added together increase the risk of future episodes of LBP.