Data over the years on vaginal intercourse among never-married adolescents, however, show a steady decline since 1988.
Freud pointed to a coldly clinical drawing of heterosexual intercourse among Leonardo's notes, which shows the lovers standing up, like mannequins.
But there is indirect support for Manuel's idea that oral sex -- which he rejects for himself -- is more likely to serve as a substitute for intercourse among his peers than it did in the late 1980's.
Researchers suggest that the decline was a result of several factors, including greater emphasis on education and employment, more motivation to delay sexual intercourse among teenagers, and whatever their limits, improved sex education and contraception.
It is not improbable that the intercourse among traders served to carry such symbols from country to country, so that modern Western numerals may be a conglomeration from different sources.
This study was conducted to examine associations with contraception methods used at last sexual intercourse among US adolescents.
Purpose: To examine the relationship between the use of two substances (alcohol and marijuana) and the occurrence of unprotected sexual intercourse among adolescent detainees.
To compare use of contraceptive methods at last heterosexual intercourse among 15 44 year-old women and men at risk of unintended pregnancy in the United States.
Substance use, in particular polydrug use, has been found to be influenced by social and contextual factors and to increase the risk of unprotected intercourse among MSM.
To compare gender differences in the factors associated with condom use at most recent voluntary intercourse among heterosexual adolescents attending a public clinic for sexually transmitted infections (STIs).
To assess patterns of contraceptive use at last intercourse among women with physical or cognitive disabilities compared to women without disabilities.
