The goal of this study is to determine if thong underwear use is associated with a higher report of urinary tract (UTI) or vaginal infections (bacterial vaginosis; BV and yeast vaginitis; YV).
A national, cross-sectional survey regarding underwear type usage and infectious history was designed and distributed to women via a crowd-sourcing service. Parametric and non-parametric statistical methods were used to compare thong wearers to never-thong wearers. Thong wearers were defined as women who had worn a thong at any point in the last 12 months.
987 respondents met inclusion criteria and completed the survey; 315 (31.9%) were never-thong wearers and 672 (68.1%) were thong wearers in the last 12 months. Thong wearers were younger, thinner, and had different sexual and hygiene behaviors than never-thong wearers, including being more sexually active. Thong wearers were more likely to report UTIs (20.4% vs 11.4%; OR;95%CI: 1.99;1.23-2.95), yeast vaginitis (22.4% vs.15.6%; OR;95%CI: 1.61;1.13-2.30), and BV (9.7% vs. 5.7%; OR;95%CI:1.77;1.03-3.03) in the last 12 months. However, a logistic regression model found that only oral sex was found to be predictive of UTI (aOR;95%CI:1.61;1.07-2.43) and BV (aOR;95%CI: 2.63;1.39-4.97); further non-cotton crotch underwear (aOR;95%CI:1.75;1.17-2.62) and oral sex (aOR;95%CI:1.51; 1.02-2.25) were predictors of YV.
We found that thong use is not associated with UTI, BV, or VY. Instead, sexual behaviors and hygiene choices are risk factors for these infections. We recommend that providers take a more complete sexual history to identify these risk factors rather than focusing on underwear as a primary risk factor.