Recalling that matrimony is a sacrament and therefore subject to the Church, let them consider and observe the laws of the Church concerning it. Let them take care lest for any reason they permit that which is an obstruction to the teachings of the canons and the decrees of the councils. They should be aware that those marriages will have an unhappy end which are entered upon contrary to the discipline of the Church or without God’s favor or because of concupiscence alone, with no thought of the sacrament and of the mysteries signified by it. (Gregory XVI. Encyclical Mirar vos, no. 12, August 15, 1832)

The faithful should also be shown that there are three blessings of marriage: children, fidelity and the Sacrament. These are blessings which to some degree compensate for the inconveniences referred to by the Apostle in the words: Such shall have tribulation of the flesh, and they lead to this other result that sexual intercourse, which is sinful outside of marriage, is rendered right and honorable. The first blessing, then, is a family, that is to say, children born of a true and lawful wife. So highly did the Apostle esteem this blessing that he says: The woman shall be saved by bearing children.’ (Catechism of Trent, 2700)

That which is good about matrimony, and that, due to which matrimony is good, could never be a sin. Now this is threefold, faithfulness, offspring, and the Sacrament. Faithfulness demands not having relations with another man or woman; the offspring demands that it be lovingly welcomed, kindly nourished, religiously educated; the Sacrament demands indissolubility of marriage and that the man or woman divorced be not joined to another even for the sake of offspring. This is as it were the rule of marriages by which rule either fruitfulness is made seemly, or the perverseness of incontinence is brought to order. (Saint Augustine. De Genesis ad litteram, Bk. 9, no. 12 – English summary)

All of the blessings of matrimony are concentrated in the parents of Christ: the offspring, fidelity and the sacrament. The offspring, in very person of the Lord Jesus; fidelity, because there was no adultery; the sacrament, because it was not ruptured by divorce. (Saint Augustine. De nuptiis et concupiscentia, Bk. I, no. 13)

God created man in his image; in the divine image he created him; male and female he created them.  God blessed them, saying: ‘Be fertile and multiply; fill the earth and subdue it.’ (Gn 1:27-28)

Lo, sons are a heritage from the Lord, the fruit of the womb a reward. Like arrows in the hand of a warrior are the sons of one’s youth. Happy is the man who has his quiver full of them! He shall not be put to shame when he speaks with his enemies in the gate. (Ps 127: 3-5)

It is for these reasons that marriage is ‘a great sacrament’; (Eph 5:32) ‘honorable in all,’ (Heb 13:4) holy, pure, and to be reverenced as a type and symbol of most high mysteries. Furthermore, the Christian perfection and completeness of marriage are not comprised in those points only which have been mentioned. For, first, there has been vouchsafed to the marriage union a higher and nobler purpose than was ever previously given to it. By the command of Christ, it not only looks to the propagation of the human race, but to the bringing forth of children for the Church, ‘fellow citizens with the saints, and the domestics of God’ (Eph 2:19); so that ‘a people might be born and brought up for the worship and religion of the true God and our Saviour Jesus Christ’ (Catechism of Trent, Chapter 8). (Leo XIII. Encyclical Arcanum Divinae sapientiae, no. 9-10, February 10, 1880)

Education is essentially a social and not a mere individual activity. Now there are three necessary societies, distinct from one another and yet harmoniously combined by God, into which man is born: two, namely the family and civil society, belong to the natural order; the third, the Church, to the supernatural order. In the first place comes the family, instituted directly by God for its peculiar purpose, the generation and formation of offspring; for this reason it has priority of nature and therefore of rights over civil society. (Pius XI. Encyclical Divini iliius Magistri, no. 11-12, December 31, 1929)

Thus amongst the blessings of marriage, the child holds the first place. And indeed the Creator of the human race Himself, Who in His goodness wishes to use men as His helpers in the propagation of life, taught this when, instituting marriage in Paradise, He said to our first parents, and through them to all future spouses: ‘Increase and multiply, and fill the earth’ (Gen 1:28). As St. Augustine admirably deduces from the words of the holy Apostle Saint Paul to Timothy (Tim 5:14) when he says: ‘The Apostle himself is therefore a witness that marriage is for the sake of generation: ‘I wish,’ he says, ‘young girls to marry.’ And, as if someone said to him, ‘Why?’ he immediately adds: ‘To bear children, to be mothers of families’ (St. Augustine, De bono coniug., ch. 24, no. 32). How great a boon of God this is, and how great a blessing of matrimony is clear from a consideration of man’s dignity and of his sublime end.  (Pius XI. Encyclical Casti connubii, nos. 10-11, December 31, 1930)

But Christian parents must also understand that they are destined not only to propagate and preserve the human race on earth, indeed not only to educate any kind of worshippers of the true God, but children who are to become members of the Church of Christ, to raise up fellow-citizens of the Saints, and members of God’s household, that the worshippers of God and Our Savior may daily increase.  […] since it is theirs to offer their offspring to the Church in order that by this most fruitful Mother of the children of God they may be regenerated through the laver of Baptism unto supernatural justice and finally be made living members of Christ. (Pius XI. Encyclical Casti connubii, no. 13-14, December 31, 1930)

Large families, far from being a ‘social malady,’ are a guarantee of the health of a people, both moral and physical. (Pius XII. Address to the Association of Large Families in Rome, January 20, 1958 – English summary)

Large families are the most splendid flower-beds in the garden of the Church; within them, as in favorable soil, happiness flourishes and sanctity ripens. […] Many times, and with good reason, it has been emphasized that it is a prerogative of large families to be the cradle of saints; we can cite, among others, the family of Saint Louis, the King of France, composed of ten children, that of Saint Catherine of Siena, from a family of twenty-five, Saint Robert Bellarmine from a family of twelve, and St. Pius X from a family of ten. Each vocation is a secret of Providence; but concerning the parents, from these facts that we can conclude that the number of children does not impede their eminent and faultless education; that the number of children, in this matter, in no way diminishes the quality, whether in regard to the physical values or the spiritual ones. (Pius XII. Address to the Association of Large Families in Rome, January 20, 1958 – English summary)

So the Church, which ‘is on the side of life’ (Familiaris consortio, no. 30) teaches that ‘each and every marriage act must remain open ‘per se’ to the transmission of life’ (Humanae vitae, no. 11). […] Called to give life, spouses share in the creative power and fatherhood of God (cf. Eph 3:14, Mt 23:9). ‘Married couples should regard it as their proper mission to transmit human life and to educate their children; they should realize that they are thereby cooperating with the love of God the Creator and are, in a certain sense, its interpreters. They will fulfill this duty with a sense of human and Christian responsibility.’ (Gaudium et Spes, no. 50, 2). […] Sacred Scripture and the Church’s traditional practice see in large families a sign of God’s blessing and the parents’ generosity. (Catechism of the Catholic Church, no. 2366-2367, 2373)

I wish to express my closeness and to assure my prayers for all the families that bear witness to fidelity in especially difficult circumstances. I encourage large families who, at times living in the midst of setbacks and misunderstandings, set an example of generosity and trust in God, in the hope that they will not lack the assistance they need. (Benedict XVI. Address by Videoconference at the conclusion of the Mass closing the sixth World Day of Families held in Mexico City, January 18, 2009)

The visit to Valencia, Spain was under the banner of the theme of marriage and the family. It was beautiful to listen, before the people assembled from all continents, to the testimonies of couples – blessed by a numerous throng of children – who introduced themselves to us and spoke of their respective journeys in the Sacrament of Marriage and in their large families. They did not hide the fact that they have also had difficult days, that they have had to pass through periods of crisis. Yet, precisely through the effort of supporting one another day by day, precisely through accepting one another ever anew in the crucible of daily trials, living and suffering to the full their initial ‘yes’, precisely on this Gospel path of ‘losing oneself, they had matured, rediscovered themselves and become happy. Their ‘yes’ to one another in the patience of the journey and in the strength of the Sacrament with which Christ had bound them together, had become a great ‘yes’ to themselves, their children, to God the Creator and to the Redeemer, Jesus Christ. Thus, from the witness of these families a wave of joy reached us, not a superficial and scant gaiety that is all too soon dispelled, but a joy that developed also in suffering, a joy that reaches down to the depths and truly redeems man. Before these families with their children, before these families in which the generations hold hands and the future is present, the problem of Europe, which it seems no longer wants to have children, penetrated my soul. (Benedict XVI. Address to the members of the Roman Curia at the traditional exchange of Christmas Greetings, December 22, 2006)

Therefore, to embrace the matrimonial state, to use continually the faculty proper to such a state and lawful only therein, and, at the same time, to avoid its primary duty without a grave reason, would be a sin against the very nature of married life. […] the will to avoid the fecundity of their union, while continuing to satisfy to tile full their sensuality, can only be the result of a false appreciation of life and of motives foreign to sound ethical principles. (Pius XII. Address to participants in the Congress of the Italian Catholic Union of Obstetricians, October 29, 1951)

We have taken advantage, throughout the last few years, of all occasions to manifest one or other essential point of the mentioned family morals, and more recently to show it as a whole; not only refuting the errors that corrupt it, but also showing plainly their meaning, their reason, their importance, their value for the happiness of the spouses, the children and of the entire family, for the stability and greater social good of the domestic home, and even for the State and the Church itself. At the center of this doctrine, matrimony appears as an institution at the service of life. (Pius XII. Speech to the participants of the National Congress of the Family Front and the Federations about the Family, November 27, 1951)

If the sincere purpose of allowing the Creator to undertake his work freely is lacking [in matrimony], human egoism will always discover new sophisms and deviations in order to, if possible, stifle the conscience and perpetuate abuses. Now, the value of the testimony of parents of large families not only consists of rejecting without hesitation, and with the strength of the facts, all intentional compromise between the law of God and the egoism of man, but also in the promptness of accepting with happiness and gratitude the inestimable gifts of God, who are the children, and in the number that pleases Him. (Pius XII. Discourse to the Directors of the Associations for Large Families, n. 1, January 20, 1958)

The transmission of human life is the result of a personal and conscious act, and, as such, is subject to the all-holy, inviolable and immutable laws of God, which no man may ignore or disobey. He is not therefore permitted to use certain ways and means which are allowable in the propagation of plant and animal life. Human life is sacred—all men must recognize that fact. From its very inception it reveals the creating hand of God. Those who violate His laws not only offend the divine majesty and degrade themselves and humanity, they also sap the vitality of the political community of which they are members. (John XXIII. Encyclical Mater et magistra, no. 193-194, May 15, 1961)

Marriage and conjugal love are by their nature ordained toward the begetting and educating of children. […] Thus, trusting in divine Providence and refining the spirit of sacrifice, married Christians glorify the Creator and strive toward fulfillment in Christ when with a generous human and Christian sense of responsibility they acquit themselves of the duty to procreate. Among the couples who fulfil their God-given task in this way, those merit special mention who with a gallant heart and with wise and common deliberation, undertake to bring up suitably even a relatively large family. (Vatican Council II, Gaudium et spes, no. 50, December 7, 1965)

The question of human procreation, like every other question which touches human life, involves more than the limited aspects specific to such disciplines as biology, psychology, demography or sociology. It is the whole man and the whole mission to which he is called that must be considered: both its natural, earthly aspects and its supernatural, eternal aspects. […] Marriage, then, is far from being the effect of chance or the result of the blind evolution of natural forces. It is in reality the wise and provident institution of God the Creator, whose purpose was to effect in man His loving design. Responsible parenthood, as we use the term here, has one further essential aspect of paramount importance. It concerns the objective moral order which was established by God, and of which a right conscience is the true interpreter. In a word, the exercise of responsible parenthood requires that husband and wife, keeping a right order of priorities, recognize their own duties toward God, themselves, their families and human society. From this it follows that they are not free to act as they choose in the service of transmitting life, as if it were wholly up to them to decide what is the right course to follow. On the contrary, they are bound to ensure that what they do corresponds to the will of God the Creator. (Paul VI. Encyclical Humanae vitae, no. 7-10, July 25, 1968)

The Church, nevertheless, in urging men to the observance of the precepts of the natural law, which it interprets by its constant doctrine, teaches that each and every marital act must of necessity retain its intrinsic relationship to the procreation of human life. […] Hence to use this divine gift while depriving it, even if only partially, of its meaning and purpose, is equally repugnant to the nature of man and of woman. (Paul VI. Encyclical Humanae vitae, no. 11-13, July 25, 1968)

The Church is certainly aware of the many complex problems which couples in many countries face today in their task of transmitting life in a responsible way. She also recognizes the serious problem of population growth in the form it has taken in many parts of the world and its moral implications. However, she holds that consideration in depth of all the aspects of these problems offers a new and stronger confirmation of the importance of the authentic teaching on birth regulation reproposed in the Second Vatican Council and in the Encyclical Humanae vitae. […] A united effort by theologians in this regard, inspired by a convinced adherence to the Magisterium, which is the one authentic guide for the People of God is particularly urgent for reasons that include the close link between Catholic teaching on this matter and the view of the human person that the Church proposes: doubt or error in the field of marriage or the family involves obscuring to a serious extent the integral truth about the human person, in a cultural situation that is already so often confused and contradictory. (John Paul II. Apostolic exhortation Familiaris consortio, November 22, 1981)

In the face of the so-called culture of death, the family is the heart of the culture of life. Human ingenuity seems to be directed more towards limiting, suppressing or destroying the sources of life — including recourse to abortion, which unfortunately is so widespread in the world — than towards defending and opening up the possibilities of life. The Encyclical Sollicitudo rei socialis denounced systematic anti-childbearing campaigns which, on the basis of a distorted view of the demographic problem and in a climate of ‘absolute lack of respect for the freedom of choice of the parties involved’, often subject them ‘to intolerable pressures … in order to force them to submit to this new form of oppression’ (25:1. c., 544) (John Paul II. Encyclical Centesimus annus, no. 39, May 1, 1991)

Thus, a man and woman joined in matrimony become partners in a divine undertaking: through the act of procreation, God’s gift is accepted and a new life opens to the future. (John Paul II. Encyclical Evangelium vitae, no. 43, March 25, 1995)