What "counts" as first sex between women? Results from a study of first sex among women who have sex with women

First sex is most often defined by first penile-vaginal intercourse (PVI) among cisgender heterosexual individuals or first anal intercourse among cisgender men who have sex with men. The importance given to penetration and PVI as the markers of first sex has contributed to the invisibility of women who have sex with women's (WSW) sexualities. Eighty-four WSW aged 16 to 25 years (M = 21.96 years, SD = 2.44; 79% cisgender) completed an online survey wherein they categorized a series of partnered behaviours as either (1) non-sexual, non-markers of first sex; (2) sexual, but non-markers of first sex; or (3) sexual and markers of first sex. Results from a non-linear principal component analysis show that there is no equivalent to PVI for first sex among WSW: direct anal or genital stimulations (either given or received; internal [e.g., vaginal, anal] or external [e.g., clitoral, vulvar]; from digital or oral stimulation, or from using toys) are categorized as markers of first sex. Behaviours such as heavy petting, caresses, and indirect genital stimulations are categorized as sexual, but non-markers of first sex. Behaviours that do not involve genital contacts, such as strip-tease or massages, are categorized as non-sexual. Triangulation with qualitative findings from the same study shows high convergence between quantitative and qualitative data in that direct genital stimulations are markers of first sex for WSW. Together, these results highlight that direct anal stimulation and the use of sex toys would be considered markers of first sex when part of WSW's early sexual encounters.