Concurrent sexual partnerships (partnerships that overlap in time) increase the spread of infection through a network. Different patterns of concurrent partnerships may be associated with varying STI risk depending on the partnership type (primary vs. non-primary) and the likelihood of condom use with each concurrent partner. We sought to evaluate co-parenting concurrency, overlapping partnerships in which at least one concurrent partner is a co-parent with the respondent, which may promote the spread of sexually transmitted infections (STIs)