The fibromyalgia syndrome (FS) is a chronic pain disorder frequently affecting women of fertile age. However, the relationship of FS and pregnancy has been given little attention. In the present retrospective analysis, based on personal interviews, the influence on FS symptomatology by pregnancy, abortion, menstruation, use of oral contraceptives, and breast feeding was investigated. Twenty-six women with an established diagnosis of FS and a total of 40 pregnancies during disease were included in the study. With the exception of one patient, all women described worsening fibromyalgia symptoms during pregnancy with the last trimester experienced as the worst period. A new change of fibromyalgia symptoms within 6 months after delivery was reported for 37 of the 40 pregnancies, to the better in four and to the worse in 33 cases, resulting in a prolonged sick leave for 14 patients. An increase in depression and anxiety was a prominent problem in the post partum period. FS had no adverse effect on the outcome of pregnancy or the health of the neonate. In the majority of patients with FS, hormonal changes connected with abortion, use of hormonal contraceptives, and breast feeding did not modulate symptom severity. A pre-menstrual worsening of symptoms was recorded by 72% of the patients. Comparing the 26 patients who had borne children during disease with 18 patients who had all their children before the onset of FS revealed a negative effect of pregnancy and the post partum period of FS and increased functional impairment and disability in the 26 patients.