Background The aims of this study are to generalise the concept of gap length between partners and to estimate the duration of four types of measures for heterosexual partnerships, called status lengths: (1) time spent as single before becoming monogamous (S–M, positive gap), (2) duration of concurrency before monogamy (C–M, negative gap), (3) duration of monogamy before concurrency (M–C) and (4) time spent in monogamy before becoming single (M–S).

Methods Medians and CIs were obtained using the US National Survey of Family Growth Cycle 6 conducted in 2002.

Results A significant gender difference was found in the monogamous to single status length (medians 38 months for women, and 19.3 months for men). Other status lengths were similar between genders (S–M: 20 women, 18 men; M–C: 16 women, 13 men; and C–M: 5 for women and men). Respondents younger than the median age at first marriage showed shorter status lengths compared to older ones. Median status lengths were comparable between heterosexuals and bisexuals. Percentage of concurrency in 1 year was 3.3% for women and 3.8% for men.

Conclusions One of the new status lengths (M–C) qualitatively indicates the transmission risk to an upcoming concurrent partner. The set of four status lengths may be useful in the context of epidemiological models with partnership dynamics.