Objectives: According to recent studies, 1.3 to 4.8% of the population of Western industrialized nations suffer from fibromyalgia, with 80 to 90% of the affected persons being women. This preponderance of women, mostly in their reproductive years, suggests an association between fibromyalgia and sex hormones.
Methods: Within the framework of a population-based cross-sectional study of 3174 female residents of Bad Säckingen aged 35 to 74 years a stratified random sample of 653 women was clinically examined and surveyed. Thirty-six of these women fulfilled the ACR criteria of fibromyalgia. Forty-four women suffered from chronic widespread pain without having fibromyalgia (chronic pain group); 408 had no chronic pain (controls).
Results: Compared to the control group, subjects with fibromyalgia have a 3.6-fold risk, while compared to the chronic pain group, there is a 3.9-fold risk of having a lower social level. Subjects with fibromyalgia drink less alcohol than subjects from the chronic pain group and the control group. After adjusting for age, multivariate analyses demonstrated that, in comparison to controls, subjects with fibromyalgia have a significantly later menarche (OR=2.2 for >14 years) and had never been pregnant (OR=0.3). The comparison of the chronic pain group and controls did not demonstrate these associations.
Conclusions: The associations with a low social level, low alcohol intake, late menarche and rare pregnancies are specific for subjects with fibromyalgia. These factors distinguish subjects with fibromyalgia from subjects with other chronic pain conditions as well as from subjects with no chronic pain. The same hormonal factors responsible for a delayed menarche and a reduced fertility may be relevant in the development of fibromyalgia.