Age at first intercourse and subsequent sexual partnering among adult women in the United States, a cross-sectional study

Background: Concurrency and serial monogamy may increase risk for STIs when gaps fall within the infectious period. This study examined the association between early sexual debut and concurrent or serial sexual partnering among heterosexual adult women. Methods: We identified 6,791 heterosexually active women, ages 21-44, from the 2006-2010 National Survey of Family Growth, a multi-stage probability sample of women in the United States. Self-reported age at first intercourse was categorized as < 15, 15-17 and >= 18 years (referent). Sexual partnering was defined as concurrency (within the same month), serial monogamy with either a 1-3 month, or >= 4 month gap between partners, or monogamy (referent) in the year prior to interview. Polytomous logistic models provided adjusted odds ratios (aOR) and 95% confidence intervals (CI). Results: Concurrent partnerships in the year prior to interview were reported by 5.2% of women. Serial monogamy with a 1-3 month gap was reported by 2.5% of women. Compared with women whose sexual debut was >= 18 years, those < 15 years at sexual initiation had 3.7 times the odds of reporting concurrent partnerships (aOR: 3.72; 95% CI: 2.46-5.62). Women < 15 years of age at sexual debut had twice the odds of serial monogamy with gap lengths of 1-3 months between partners (aOR1-3 months: 2.13; 95% CI 1.15-3.94) as compared to women >= 18 years at sexual debut. Conclusions: Sexual debut at < 15 years is associated with both concurrency and serial monogamy with 1-3 month gaps between partners in U.S. women aged 21-44.