of the time,’ and ‘always.’ If the girl responded ‘sometimes’ or more often, she was also asked which form(s) of birth control she used. Following prior research (e.g., Locke and Newcomb 2008), a risky sex index was created from four dichotomized items assessed at age 16: i) had sexual intercourse with two or more partners in the past year; ii) did not ‘always’ use birth control, and/or did not use condoms; iii) had been pregnant in the past year; and iv) had an STI in the past year (see Table 1). Of girls reporting STIs, 71.4% also reported inconsistent birth control, 42.9% had two or more sexual partners, and 28.6% had become pregnant in the past year. Of girls who had become pregnant, 85.7% reported inconsistent use of birth control, 28.6% had two or more partners and 7.1% contracted an STI. Becoming pregnant and contracting an STI were thus not fully accounted for by either reported number of sexual partners or use of birth control, including condoms. Of those girls who had ever had sexual intercourse, the ages of initiation were as follows: 3.9% at age 12, 3.9% at age 13, 11.8% at 14, 21.9% at 15 and the remaining
