Our primary analyses coded both women who had never used cannabis and women who had used cannabis but at age 17 or older as unexposed members of twin pairs. Discordant twin analyses were repeated in women who reported a history of sexual activity as well as cannabis use (N=1368). Even in the modest number of 52 MZ pairs discordant for adolescent cannabis use (Table 2), the twin who used cannabis prior to age 17 was at 3 times increased odds of reporting rVUS relative to her genetically identical co-twin who reported cannabis use but at age 17 or later. Thus, even within cannabis users, earlier onset of cannabis use is associated with a unique increase in likelihood of rVUS.
