Here is a summary of Amoris Conjugalis :
Conjugal love which makes marriage a true union of persons is not exhausted in mutual self giving. Married people can establish a true community only if their love is made fruitful in the creation of new life, God created human beings male and female so that joined together in the bonds of love, they help each other grow in holiness and prepare their children, the fruit of their love, for a truly human life.
A married couple will decide according to conscience before God the number of children they will have, according to the teachings of the church. Married couples need morally good means for the regulation of conception if they are to cultivate the essential values of marriage. It is right that man should intervene in physiological processes. This is in accordance with the mission which God has given to men, whom he has made his co-operators.
Then comes the paragraph quoted in my previous post.
The tradition of the church as regards conjugal relations developed in argument and conflict with heretics such as the Gnostics, Manicheans, and the Cathari, all of whom condemned procreation as evil. In the course of centuries the words in which this tradition was expressed, and the reasons on which it was based, were proper to the times.
It is not to contradict the genuine sense of this tradition if we speak of the regulation of conception to favour fecundity in the totality of married life. The reasons for this evolution of doctrine are social changes in matrimony and the famlly, especially in the role of women, new bodies of knowledge in biology, psychology and sexuality. Also the sense of the faithful that the condemnation of a couple to a long, and often heroic, abstinence to regulate conception, cannot be based on the truth.
In exercising responsible parenthood and deciding on the size of their families, married couples will thoughtfully take into account both their own welfare and that of their children, those already born and those which may be foreseen. But their conscience must always be in conformity with the Divine Law and submissive to the teachings of the church.
Episcopal conferences should be concerned that priests and married lay persons have a more moral and spiritual understanding of Christian matrimony. Christianity does not teach an ideal for a small number of elect, but the vocation of all to the essential values of human life,
Every responsibility and task of the conjugal and family community shines with the clear light of love of one's neighbour. May the spirit of Christ's love enable married couples, parents and children, to understand more deeply the profound relation between love of God and love of one another.
I have taken this summary of Amoris Conjugalis and the paragraph in my previous post, from the Final Report of the Pontificial Commission on Population, Family and Birth in OTL, in the book The Encyclical that Never Was: The Story of the Pontificial Commission on Population, Family and Birth, 1964-1966 , by Robert Kaiser, London: Sheed and Ward, 1987