Smoking and pregnancy-related pelvic pain

Objective: To investigate possible associations between smoking and pregnancy-related pelvic pain. Design: Nested case-control study. Setting: Denmark 2000-2001. Population: The Danish National Birth Cohort. Methods The women were interviewed twice in pregnancy and twice after childbirth. The first pregnancy interview provided information on smoking and possible confounding factors, whereas the first interview after birth addressed case identification. Cases (n = 2302) were defined on the basis of self-reported pelvic pain, and controls were selected among women who did not report pelvic pain (n = 2692). Logistic regression analysis was used to estimate associations between smoking and pelvic pain. Main outcome mreasue: Pregnancy-related pelvic pain. Results: Compared with non-smokers, women who smoked during pregnancy had an adjusted odds ratio of 1.2 (1.0-1.4) for overall pelvic pain, similar to women who stopped smoking in early pregnancy 1.3 (1.1-1.7). The equivalent adjusted odds ratio for severe pelvic pain was 1.2 (1.0-1.5) for smokers, and 1.5 (1.2-1.9) for women who stopped smoking. Smoking intensity, measured as number of cigarettes smoked per day, was associated with pelvic pain in a dose-response pattern. Information about smoking was collected prospectively, which makes it unlikely that differential recall alone explains the results. Conclusions: Smoking was associated with pregnancy-related pelvic pain, with a dose-response pattern between reported smoking intensity and pelvic pain. These findings suggest a possible new risk factor for a common ailment during pregnancy.