The first objective of this research was to compare risk factors for three uterine leiomyomata (UL) subtypes (submucosal UL, intramural/subserosal UL, and diffuse only) among African-American and Caucasian women. The second objective was to investigate the association between UL and self-reported SUI in premenopausal women. Data were from 35 to 49 year old premenopausal African American and Caucasian women enrolled in the National Institute of Environmental Health Sciences Uterine Fibroid Study. The cross-sectional study of risk factors for UL subtypes included 986 premenopausal women (581 African-American, 405 Caucasian). For women in both ethnic groups, associations with age at ultrasound examination, age at menarche, body mass index, and current physical activity were similar for all three UL subtypes. Inverse associations estimated for pregnancies after age 24 were stronger for the submucosal UL subtype than the other two subtypes. Current smoking was positively associated with the diffuse only subtype, but was not associated with focal UL subtypes in either ethnic group. The study of UL and SUI included 798 premenopausal women (446 African- American and 352 Caucasian). The estimated prevalence of SUI was higher among women with UL than among women without UL. Associations were slightly stronger for medium (2-4cm) and large ([greater than or equal to] 4cm) UL, but anterior location was not associated with further increase in prevalence. Women with very large uterine volume (above the 83rd percentile for the population) reported more SUI than those with small uterine volume (bellow the 33rd percentile). There was no clear evidence of effect modification by ethnicity or parity. The two studies have improved upon prior research by identifying and characterizing UL based on ultrasound examinations (instead of including diagnosed UL only), and by including both African American and Caucasian women. Results suggest that future studies of UL etiology should distinguish the focal UL subtypes from the diffuse only subtype to account for potential differences in etiologic mechanisms, and that treatment for larger UL might enhance SUI treatment in some women
