Sexual intercourse (or coitus or copulation) is principally the insertion and thrusting of the penis, usually when erect, into the vagina for sexual pleasure, reproduction, or both.

Sexual intercourse during cence is a significant and complex event. It leads to a radically new understanding of one’s identity as a physically developing person, and it is a major psychological milestone on the road to adulthood.1

Background The timing of sexual intercourse in relation to ovulation strongly influences the chance of conception, although the actual number of fertile days in a woman’s menstrual cycle is uncertain.

Fig. 1. Intact adult penis: This illustration represents an average normal adult human penis. The head of the penis (glans) has a covering, called the foreskin (prepuce).

A combined analysis of all studies of HIV-transmission risk undertaken to date in high-income countries has found that unprotected vaginal intercourse with an HIV-positive man who is chronically infected and not on antiretroviral treatment (ART) carries an estimated 0.08% risk of infection for the woman per sexual act.

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This chart shows average age at first sex by country. Average age at first sex among 44 countries: 18.4

All About Sexuality and Sexual Health. Comprehensive and friendly resources providing straightforward answers to questions about sexual health, sex tips and techniques, and articles on sex research, science, culture, and more.

This statistic shows the average number of sexual partners by countries in 2005. According to the survey, people in the United States have had an average of 10.7 sexual …

Explains various aspects of female sexuality and provides advice on relationships, sex, and sexual problems.