Objective STIs are the most common infections among adults. Concurrently, pubic hair grooming is prevalent. Small-scale studies have demonstrated a relationship between pubic hair grooming and STIs. We aim to examine this relationship in a large sample of men and women.

Design We conducted a probability survey of US residents aged 18–65 years. The survey ascertained self-reported pubic hair grooming practices, sexual behaviours and STI history. We defined extreme grooming as removal of all pubic hair more than 11 times per year and high-frequency grooming as daily/weekly trimming. Cutaneous STIs included herpes, human papillomavirus, syphilis and molluscum. Secretory STIs included gonorrhoea, chlamydia and HIV. We analysed lice separately.

Results Of 7580 respondents who completed the survey, 74% reported grooming their pubic hair, 66% of men and 84% of women. After adjusting for age and lifetime sexual partners, ever having groomed was positively associated with a history of self-reported STIs (OR 1.8; 95% CI 1.4 to 2.2), including cutaneous STIs (OR 2.6; CI 1.8 to 3.7), secretory STIs (OR 1.7; CI 1.3 to 2.2) and lice (OR 1.9; CI 1.3 to 2.9). These positive associations were stronger for extreme groomers (OR 4.4; CI 2.9 to 6.8) and high-frequency groomers (OR 3.5; CI 2.3 to 5.4) with cutaneous STIs, and for non-extreme groomers (OR 2.0; CI 1.3 to 3.0) and low-frequency groomers (OR 2.0; CI 1.3 to 3.1) with lice.

Conclusions Among a representative sample of US residents, pubic hair grooming was positively related to self-reported STI history. Further research is warranted to gain insight into STI risk-reduction strategies.