性行為的基本類型

2. 異性性交: 異性生殖器性交

性交合注意事項

考慮到當前HIV/AIDS的流行和世界範圍其它性傳播疾病（STDs）增加的因素，男女都應該要瞭解與新近偶遇認識的和不熟識的性伴經由陰道性交（性交合）的感染風險。甚至熟識的性伴，如果他們另有偶遇的性伴，那麼他們也許不知不覺就已經感染了性傳播疾病或愛滋病。對於接受可能受到感染的精液的女子，這種感染的風險更大（換一句話說，這就意味著，妓女冒著經由男性顧客感染的風險比男性顧客經由該妓女感染的風險更大。）男性性伴從感染的陰道分泌液或月經血感染的風險較低，但是也極力建議他們使用安全套。從世界範圍來看，陰道性交現在是HIV/AIDS傳播的主要途徑。

In view of the current HIV/AIDS pandemic and the world-wide increase of other sexually transmitted diseases (STDs), both females and males should understand the risk of infection through vaginal intercourse (coitus) with casual, new, and unfamiliar partners. Even familiar partners may unknowingly have become infected if they, in turn, had casual partners. The risk is greater for the female partners receiving possibly infected semen. (This means, among other things, that female prostitutes run a greater risk of becoming infected through their male customers, than vice versa.) The male partners run a lower risk from infected vaginal fluid or menstrual blood, but they are also well advised to use a condom. World-wide, vaginal intercourse is now the main path of HIV/AIDS transmission.

HIV/AIDS risk
Casual partners may be infected with HIV/AIDS without knowing it. Therefore, unprotected vaginal intercourse with them carries a high risk of infection, especially for the “receiving” partner.
Courtesy BZgA, Cologne