Recognizing that some of the studies potentially included the presence of confounding factors, such as the possibility that women who regularly perform fellatio and swallow semen also engage in more frequent intercourse, the researchers also noted that, either way, "the data still overwhelmingly supports the main theory" behind all their studies—that repeated exposure to semen establishes the maternal immunological tolerance necessary for a safe and successful pregnancy.
Laws of some jurisdictions regard oral sex as penetrative sex for the purposes of sexual offenses with regard to the act, but most countries do not have laws which ban the practice itself, in contrast to anal sex or extramarital sex.
Spitting and/or swallowing of the ejaculatory fluids or giving a pearl necklace may cause different sexual stimulations.
The breakdown products are then absorbed as a negligible quantity of nutrients.
However, there is a potential risk of pregnancy if semen comes in contact with the vaginal area in some way, such as semen in the ejaculate finding its way onto fingers, hands, or other body parts, which then comes in contact with the vaginal area.
Links have been reported between oral sex and oral cancer with human papillomavirus (HPV)-infected people.
In 2005, a research study at Malmö University's Faculty of Odontology suggested that performing unprotected oral sex on a person infected with HPV might increase the risk of oral cancer.
Plastic wrap may also be used as a barrier during oral sex, but there exists no conclusive scientific research regarding how effective it may or may not be at preventing disease transmission.
Certain kinds of plastic wrap are manufactured to be microwaveable and are designed to have pores that open when heated, but there also exists no scientific research on what effect, if any, this has on disease transmission when used during oral sex.
However, the transmission risk for oral sex, especially HIV transmission, is significantly lower than for vaginal or anal sex.
Oral sex may be practiced by people of any sexual orientation.
An act of group sex restricted to one woman giving oral sex to several men is referred to as a gangsuck, blowbang or lineup, all derivatives of the slang term gang bang for group sex. Oral sex is commonly used as a means of preserving virginity, especially among heterosexual pairings; this is sometimes termed technical virginity (which additionally includes anal sex, mutual masturbation and other non-penetrative sex acts, but excludes penile-vaginal sex).