Primary dysmenorrhea and risk of preterm delivery.

Little is known about the mechanism and biochemical pathway of preterm delivery. Some drugs used to treat preterm labor are also useful for the treatment of primary dysmenorrhea. This study attempted to evaluate the association between primary dysmenorrhea and preterm delivery from an epidemiological perspective. A nested case-control study was conducted; 329 singleton preterm delivery cases were investigated, in aggregate and in subgroups (spontaneous preterm labor and preterm premature rupture of membranes). Concurrently, 329 singleton gravid women with term delivery served as controls. Medical charts and records provided information about the maternal history of dysmenorrhea, index pregnancy outcome, and demographic characteristics. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using the multiple logistic regression method. Gravid women with a history of primary dysmenorrhea had no more risk of preterm delivery than those without a history of primary dysmenorrhea (adjusted OR, 1.16; 95% CI, 0.95 to 2.19; p=0.37). However, for subgroup analysis, gravid women with severe primary dysmenorrhea were associated with an adjusted 2.73-fold risk of spontaneous preterm delivery (95% CI, 1.49 to 4.95; p=0.02), and with an adjusted 1.51-fold risk of preterm premature rupture of membranes (95% CI, 0.68 to 3.22; p=0.31). Severe primary dysmenorrhea is associated with an increased risk of spontaneous preterm delivery. A common pathophysiologic pathway may exist between these two disorders. Further in-depth biochemical and molecular studies are necessary to explore this phenomenon.