性行为的发展

从个人层面看，成人期通常是男女打算做父母的时期。在当代社会，在青春期做父母不是典型的社会行为模式，并且常常是非意愿怀孕的结果。相反，现在大多数成人有意识地选择生养孩子。他们也选择什么时候生养孩子，生养多少和以多长间隔时间生养孩子。他们利用现在可供利用的避孕方法，把性欲行为与生殖行为当作各自独立的事物看待。

的确，这种观点被许多担忧人口无节制增长的政府所鼓励。中国就是一个很好的例子，在那里，在城市“每对夫妻生一个孩子”的官方政策（但是，在农村，如果第一个孩子是女孩，则实行“每对夫妻生两胎”的政策，并且对少数民族的政策更为宽松）[1]显然而然地告诉了每一个城市公民，那就是性与生殖不再是一个不可分解的链环。

另一方面，一些宗教传统仍然坚持性与生殖的链接。例如，天主教要求性行为应该始终保持“对新生命开放的可能状态”。按照这种宗教戒律，大多数的避孕措施因而都是“人为的”和不道德的。

当今，在大多数国家，使用避孕措施的决定留待个人凭良心自主选择。对于那些不孕不育的夫妻处理性与生殖的关系中，也是如此。一些不孕不育夫妻接受现实，认为这是上帝的旨意，会适应没有孩子的生活；其他不孕不育夫妻选择了收养孩子；还有一些这样的夫妻利用许多现代的抗不孕/不育方法之一种来生养自己的孩子。

Stages of Development: Adulthood

Reproductive Behavior 1

On the individual level, adulthood is usually the time when females and males decide to become parents. In modern societies, parenthood in adolescence is not typical and often the result of an unwanted pregnancy. In contrast, most adults now make a conscious choice to have children. They also choose when to have them, how many, and at what intervals. Taking advantage of the now available methods of contraception, they see erotic and reproductive behavior as separate issues.                                                                              Indeed, this view is encouraged by many governments concerned about unchecked population growth. A good example is China, where the official policy of “one child per couple” in urban areas (but there is a policy of "two embryos per couple", if the first child is a girl  in the country, and  there is even a largely loose policy in minorities )makes it clear to every citizen that sex and reproduction are no longer inextricably linked.
On the other hand, some religious traditions still insist on this linkage. The Catholic Church, for example, demands that sexual intercourse should always remain “open to the possibility of new life”. According to this doctrine, most forms of contraception are therefore “artificial” and immoral.
In most countries today, the decision to use contraception is left to the individual conscience. This is also true of the ways in which couples deal with infertility. Some accept it as the will of God and adjust to a life without children, others choose adoption, and still others take advantage of one of the many modern methods of overcoming Infertility.