Adaptive immunity requires antigenic priming of the lymphatic system. As lymphatic tissue is abundant in the oropharynx, oral sex could lead to effective immune stimulation and prevent pelvic inflammatory disease (PID).
To determine whether oral sex could be a protective factor for PID.
The relationship between self-reported oral sex and endometritis was analysed among 619 women with clinically suspected PID who participated in the PID Evaluation and Clinical Health (PEACH) study.
Nearly one quarter of participants reported oral sex in the past 4 weeks. These women also reported a higher number of sexual partners, a new partner within the past 4 weeks, and a higher frequency of sexual intercourse (all p< 0.03). They were more likely to smoke (p<0.0001) and use alcohol (p<0.004) and recreational drugs (p<0.02). Participants reporting oral sex were significantly less likely to be black or to have a positive test for Neisseria gonorrhoeae (7.8% vs 21.6%, p= 0.001).
Women who disclosed oral sex were significantly less likely to have endometritis after adjusting for race, number of partners, recent new partner, smoking, alcohol use, and drug use (adjusted OR 0.5 (0.3 – 0.8)).
This is the first paper showing a negative association between oral sex and endometritis. This may be mediated by a protective immune response in the genital tract following priming in the pharynx. This hypothesis needs to be tested in further studies.