Objectives: To compare variables of sexual behaviour and incidence of genital infections among women of different racial origins and lifestyles. Design: A prospective cross sectional study of sexual behaviour reported by a standardised self administered questionnaire in new patients who presented for screening and diagnosis. Setting: A genitourinary medicine clinic in west London. Subjects: 1084 consecutive women newly attending in 1992. Main outcome measures: Variables relating to sociodemographic status, sexual lifestyle, condom use, sexually transmitted diseases, and other genital infections stratified by racial origin. Results: There were 948 evaluable women, of whom 932 (98.3%) were heterosexual and 16 (1.7%) were lesbian. Previous heterosexual intercourse was reported by 69% of lesbian women and their most frequent diagnosis was bacterial vaginosis (38%). The majority of heterosexual women were white (78%) and 16% were black. The black women were more likely to be teenagers (18% cf 8%; p=0.0004) or students (28% cf 15%; p=0.0008), and to have had an earlier coitarche (48% cf 38% before aged 17; p<0.004). They also had a higher proportion of pregnancies (58% cf 38%; p<0.00001) and births (38% cf 20%; p<0.00001). The white women showed significantly more sexual partners during the preceding year (p=0.004) and in total (p<0.00001) and more reported non-regular partners (48% cf 35%; p=0.004) with whom they were more likely to use condoms (p=0.009). However, the black women were more likely to have gonorrhoea (7% cf 2% p<0.0003), chlamydial infection (12% cf 5% p<0.002), trichomoniasis (10% cf 2% p<0.00001), or to be sexual contacts of men with non-gonococcal urethritis (19% cf 12% p<0.02). They were less likely to have genital warts (3% cf 12% p=0.002). Logistic regression showed that all these variables were independently associated with the black women. The Asian women (2%), none of whom had a sexually transmitted disease, had commenced intercourse later (mean 19.7 years) than both black women (mean 16.8 years) and white women (mean 17.6 years). Conclusions: Sexual intercourse commenced approximately 1 year earlier in the black women, who were more likely to have become pregnant, had children, and to have acquired a bacterial sexually transmitted infection than were the white women.
