Sexual intercourse

Lore & Background

Sexual intercourse is defined variably across cultures and legal systems. While penile–vaginal penetration is the most common definition, many also consider anal and oral sex as intercourse. The World Health Organization notes that non-English languages use different words with slightly different meanings. Researchers often focus on penile–vaginal sex due to cultural preoccupation, but this can limit understanding of non-heterosexual behavior and non-vaginal activities.

Reader's Guide

Sexual intercourse carries both biological and social significance. It is the primary means of human reproduction, but also serves as a source of pleasure and emotional bonding. Safer sex practices are recommended by health professionals to reduce transmission of sexually transmitted infections.

Legal restrictions vary by jurisdiction, covering acts such as adultery, incest, sex with minors, prostitution, rape, and sodomy. Religious beliefs influence personal decisions about virginity, premarital sex, and public policy. Among non-human animals, copulation typically occurs during estrus for most mammals, but bonobos, dolphins, and chimpanzees engage in sex for pleasure and social bonding regardless of fertility cycles.

Did You Know?

• Some men in Africa consider condom-protected sex not 'real sex' because condoms prevent direct skin-to-skin genital contact.
• The term 'coitus' is derived from the Latin word 'coitio' or 'coire', meaning 'a coming together or joining together'.

Stimulation

Sexual intercourse and other sexual activities involve physiological and psychological stimulation, including various sex positions and sex toys. Foreplay often precedes sexual activity, leading to arousal such as penile erection or vaginal lubrication. People may be as sexually satisfied by kissing, erotic touching, or being held as by intercourse itself.

Unlike non-primate females, who copulate only during estrus and assume the lordosis position, human women can engage in intercourse at any point in the menstrual cycle, and human pheromone detection has only residual effects. During coitus, partners orient their hips to create friction through back-and-forth penile movement, typically continuing until orgasm. For women, clitoral stimulation is significant; 70–80% require direct clitoral stimulation to orgasm, though indirect stimulation via vaginal intercourse may suffice. The woman-on-top position or the coital alignment technique can maximize clitoral stimulation.

Anal sex involves stimulation of the anus, anal cavity, sphincter, or rectum, often via penile insertion, sex toys, fingers, or anilingus. Oral sex includes mouth and throat stimulation of genitals or anus, sometimes involving ingestion of semen or vaginal fluids. Fingering involves digital manipulation of the clitoris, vulva, vagina, or anus for arousal.

Safe sex and birth control

Safe sex methods include non-penetrative acts, and heterosexual couples may use oral or anal sex for birth control. However, pregnancy can occur from anal sex or other activities if sperm is deposited near the vaginal entrance and travels via lubricating fluids; sperm may also be transported by fingers or other body parts. Condoms are recommended for preventing sexually transmitted infections; correct and consistent use of latex condoms reduces HIV/AIDS transmission risk by approximately 85–99%. Condoms are rarely used for oral sex, and research on condom use for anal and oral sex is limited.

Abstinence from vaginal, anal, and oral intercourse is the most effective way to avoid STIs. Birth control decisions are influenced by cultural factors such as religion, gender roles, or folklore; in predominantly Catholic countries, fertility awareness and the rhythm method are emphasized. Worldwide, sterilization is common, and the intrauterine device is the most common and effective reversible contraception. In developing countries, one in three women give birth before age 20, and 90% of unsafe abortions could be prevented by effective contraception.

Prevalence

Penile–vaginal penetration is the most common form of sexual intercourse, with most heterosexual couples engaging in it nearly every sexual encounter. It is the most prevalent sexual behavior among all ages and ethnicities, the most frequently studied behavior, and the most widely endorsed and practiced sexual act. Oral sex is commonly practiced by sexually active male-female and same-gender couples of various ages, including adolescents, and is significantly more common than anal sex.

Among men, vaginal intercourse is practiced more than insertive anal intercourse, though 13–15% of men aged 25 to 49 engage in insertive anal intercourse. Receptive anal intercourse is infrequent among men, with about 7% of men aged 14 to 94 reporting being the receptive partner. Fewer women report anal sex than other partnered behaviors; an estimated 10–14% of women aged 18 to 39 practiced anal sex in the past 90 days, most doing so once a month or a few times a year.