Penile–vaginal intercourse, or just vaginal intercourse, is the insertion of an erect penis into a vagina. It is the primary form of copulation in mammals, and of penetrative sexual intercourse in human sexuality. Synonyms are: vaginal sex, coitus (Latin: coitus per vaginam), (in elegant colloquial language) intimacy, or (poetic) lovemaking.
Various sex positions can be used during vaginal sex, and sometimes additional lubrication is desirable. Following penile insertion, additional stimulation is often achieved, by either partner, through rhythmic pelvic thrusting, or a gyration of the hips, among other techniques. The biological imperative is to achieve male ejaculation so that sperm can enter the female reproductive tract and fertilize the egg, thereafter beginning the next stage in human reproduction – pregnancy.
Biological function
The desire for sensual pleasure, or sometimes explicitly sexual pleasure, is usually the main motivation for humans, or sometimes the wish to have a baby, or to have more children. The biological function of vaginal intercourse is human reproduction. During coitus without a condom, sperm enter the vagina, first with the pre-ejaculate and then a larger amount through male ejaculation.Encyclopedia.com: Penetration. March 2022.
Sperm swim through the cervix and the uterus into the fallopian tubes of the woman. If they meet a fertilisable egg cell after or during an ovulation, or if an ovulation occurs hours or days later, one sperm can fertilize it. The resulting zygote develops into the early embryonic stages and, in the meantime, migrates from the fallopian tube into the uterus. The nidation of the embryo called blastocyst at this stage of development, with the beginning of the production of hCG marks the beginning of a pregnancy.Neil A. Campbell, Jane B. Reece: Biologie. Spektrum-Verlag, Heidelberg/ Berlin 2003, ISBN 3-8274-1352-4, page 1178–1187 Without contraceptives, during a woman's fertile days, there is a relatively high probability that conception will follow.
For people who do not want (another) child, contraception has made it possible to separate vaginal intercourse from its biological function of procreation. Worldwide, about 57 per cent of couples with women of reproductive age use modern methods of contraception.
Since there is no mating season (estrus) in humans, the partners can have penile–vaginal intercourse distributed over the menstrual cycle regardless of the time of ovulation, even when the woman is already pregnant and after the menopause.Desmond Morris: The Naked Ape: A Zoologist's Study of the Human Animal The principles of safer sex eliminate the reproductive function. Couples who wish to have offspring can avail themselves of the tests for sexually transmitted infections recommended by the WHO, so that after ruling out or treating any detected infection, they can have penile–vaginal intercourse without using a condom.WHO: Sexually transmitted infections (STIs).Aids-Hilfe Schweiz: Family planning .Mein Baby, mein Kids to go: Gesundheits-Check-up bei Kinderwunsch. 2023.Sanitas: pre-pregnancy health check-up. 2023.Federal Ministry of Health (Germany): Pregnancy check-up and chlamydia screening.Universitätsmedizin Essen, Universitätsklinikum für Dermatologie: HIV, pregnancy and family planning. 2023.WHO: Planning pregnancy and having safe sex.
Legal situation Vaginal intercourse between private individuals is part of their private sphere. Sexual intercourse between an adult and a young person is generally only permitted after the age of consent in the respective country has been reached, though some countries/jurisdictions have special exceptions to this rule. These exceptions may include when the minor is legally married to the adult or within no more than a specified age gap with the adult. Nowadays, intimate intercourse between unmarried teenagers is permitted and common in many countries. Lack of sexual education about contraception often leads to teenage pregnancy. In many countries, after marriage, the first cohabitation is considered a (sexual) "consummation of marriage". In every country of the world, vaginal intercourse performed without the consent of the other person constitutes rape.
Psychological aspects A desire for pleasure is a natural motivation for sex in general. Human intimacy favours a pleasurable experience.Tobias Ruland: Die Psychologie der Intimität. Klett-Cotta-Verlag, Stuttgart 2015. ISBN 978-3-608-98037-0. For people who prefer non-committal sex, emotional closeness plays a lesser role.Jessie Sage: If you require an emotional connection to feel any sexual connection, you are not alone. In: pghcitypaper.com vom 14 August 2019. In studies consensual vaginal intercourse has been associated with signs of better physiological and psychological functions. In women, regular orgasms during vaginal sex correlate positively with passion, love and relationship quality.
In experimental studies with men and women whose hormone levels were examined, one having vaginal intercourse and the other self-pleasuring to orgasm, it was found that in both sexes the increase in prolactin was 400% higher after vaginal intercourse than after masturbation. This is interpreted to mean that vaginal intercourse is physiologically more satisfying. In satisfying relationships, positive effects on health and well-being have been proven. One study (2012) showed a stress reduction effect for both partners in satisfying relationships, but not in unsatisfactory relationships.BKK-web TV Gesundheitsmagazin: Sex im Alter. 26 February 2010. As preliminary for the natural procreation of a new human being, for females, penile–vaginal intercourse is connected with various attributes like psychological and sacramental aspects beyond the reproductive function. Sometimes sex is also driven by motives like to degrade, to punish, or to overcome loneliness and boredom.
In 2006, the WHO reported a worldwide prevalence of between 8% and 21.1% of painful vaginal sex for women. In a U.S. study, about 30% of women and 7% of men reported pain, for most, only mild and of short duration. This study found that a large percentage of Americans do not talk about the pain with their partner. In a Swedish study of young women aged 18 to 22, as many as 47% reported pain, but they said they did not want to interrupt the sex act. Some pretended to enjoy it instead of giving the man any feedback. The most common reason was that they put the man's pleasure above their own and tended toward submissiveness during sex. Data from an online survey in the United States suggest that a proportion of men engage in sexual behaviours described as dominant and purposeful, in which they mimic behaviors seen in porn. Unless a woman's pain has a physical cause, it is often related to impatient partner action or lack of open communication. The prevention of sexual disappointment and dyspareunia caused by the behaviour of the male partner is summarized by Betty Dodson in the following words:
Description
In all mammals including humans, penile penetration of the vagina is an instinctual behaviour serving the continuation of the species.Encyclopedia.com: Penetration.Desmond Morris: The Naked Ape. In humans, learned behaviour also plays an important role (sexual scripts).Diane Glelm: Is Sex Natural? In: Psychology Today., 19 February 2020. From Shere Hite, there is the suggestion to define onset not by penetration, but by the covering of the vulva by the penis.
Preparation for vaginal coitus usually involves foreplay in the form of various combinations of caresses, petting, manual sex, oral sex. For the woman, physical sexual arousal and clitoral erection resulting from the foreplay are the prerequisites for the reaction of the intravaginal G-spot.
The sex positions, the pelvic movements of the woman and the man, how slowly or quickly they are performed, and the lesser or greater depth influence the two arousal curves. Duration can be influenced by positions, gentle or stronger movements, and by touching erogenous zones with the hands.Alex Comfort: The Joy of Sex 1972. The needs for movements are individually different for both women and men. For women, pelvic floor training and active movements of their pelvis during vaginal intercourse increase the chance of orgasm. A man's arousal curve usually rises faster, while women need plenty of time. According to an investigation of 2005 the time from penile insertion to male orgasm, the intravaginal ejaculation latency time (IELT), varies between 0.55 and 44.1 minutes. Sexually experienced men use delaying techniques to give their female partner the time she needs. Most men can learn to intentionally delay their own arousal and orgasm by practicing this doing masturbation.
The reason why men are faster in achieving orgasm is that the glans penis is constantly enveloped by the vagina; it is continuously stimulated, making it likely that moving it in and out repeatedly will cause him to have an orgasm relatively soon. In women, the glans clitoridis lies at a distance to the vaginal entrance, often without physical contact.
The clitoral glans has an essential function in triggering sexual arousal and then orgasm, For many women, the movement of the penis in the vagina causes only a limited increase in their arousal. Many women reach orgasm when both the extragenital parts of the clitoris and the erogenous zones inside the vagina are continuously stimulated simultaneously for long enough. Sexual arousal can increase to the point where one or both partners experience an orgasm either in succession or simultaneously. The hypothesis of two modes of female orgasmvaginal or clitoralis not tenable. Rather, it is a complex reaction in which all organ systems of the human body are involved.Volkmar Sigusch: Sexualitäten. Eine kritische Theorie in 99 Fragmenten. Frankfurt a. M., New York 2013 – Without clitoral stimulation, 23.3% of women reach orgasm during vaginal intercourse, with simultaneous clitoral stimulation 74%.Stefanie Gonin-Spahni, Michèle Borgmann, Sandra Gloor, Hansjörg Znoj: Sexualität Beziehung und Gesundheit. In: SeBeGe Newsletter, Informationen zum Projekt SeBeGe, Institut für Psychologie der Universität Bern, August 2019, page 10.
When the man is sitting upright with the woman sitting on his lap, she can rub her clitoris against his pubic bone.Lotus-Stellung: All you need to know about the sensual Kamasutra sex position. Cosmopolitan, 12. January 2021. In lateral coital position, there are also possibilities for clitoral stimulation while the penis is moving inside. In the flanquette position, the man can give some pressure with his thigh to her mons pubis and the clitoral glans.
Another variation of vaginal sex is with lesbians who use a single or double-sided dildo.
Injury risks
In a woman with an intact moist vaginal mucosa, friction by the penis is painless. In case of insufficient vaginal lubrication or excessive temporal extension of the coitus, the mucous membranes may become sore due to mechanical irritation. If sand gets into the vagina on a beach or in an unclean dwelling, small abrasions occur in the vagina and on the glans penis. A vaginal douche has physiological disadvantages. The sand is excreted by the natural self-cleaning of the mucous membrane.
The length of the stretched vagina varies from person to person. The mean value is which corresponds to the average length of the human penis. At rest, the vagina is considerably shorter. In a study from 1993, the mean value was given as 9.2 cm, in a study from 2006, only 6.27 cm with a variation of the lengths between 4.1 and 9.5 cm.