Specifically Catholic - a call to charity among the non-contracepting

Many people have claimed to me that the Catholic Church teaches that Catholic married couples can only avoid pregnancy for "grave reason."  

The Church does not teach that “grave reasons” are needed before using NFP to avoid pregnancy.   That is a mistranslation, however commonly repeated it may be.  And it is a line spouted over and over again.   

Humanae Vitae is the most authoritative and arguably most important statement of the Magisterium about this.  In the official Latin it cites seriis causis (“serious causes” or “serious reasons”) as necessary for the intent of a married couple to avoid conception to be licit.  That is, a couple needs something more than a trivial or selfish reason to avoid pregnancy.  This reason does not have to rise to the level of super-serious or life-threatening, which is what most English-speaking people imagine when they hear the word "grave."  

In addition to Humanae Vitae, there is also Pius XII’s October 29, 1951 address to Italian Catholic midwives.  The most relevant paragraph – in the original Italian – first mentions serios motivos – “serious motives.”  The text does also, at the end of the preceding paragraph and later in the relevant one, mention "grave motivo" and "graves razones."  The translation of the Italian grave(s) as “grave” is more excusable than the translation of the Latin seriis or the Italian serios as “grave.”  However, it is still a mistranslation.  The Italian grave (and the Latin gravis) essentially mean “heavy” or “weighty” – as opposed to “light” or “trivial”.   In other words – “serious.”  Furthermore, it is fairly clear from the wording of the paragraph that Pius is using graves as a synonym for serios – i.e., “serious.” In addition, one has to read that address in the context of his November 11, 1951 address to the Congress of the Family Front and of the Association of Large Families.  There he says that the moral limits surrounding the avoiding of pregnancy by natural means are “truly very wide."  Thus, they would encompass all those reasons that would be called “serious” – not merely a small subset of such super-serious reasons that would in English be called “grave.”

The Church calls couples to be generous to life, but also to discern how many children to have based on their relationship with God, spouse, and with children already born, and their obligations to society.  The answer will be different for each couple.  For some, a family of 13 children is both responsible and generous.  For others a family of one child is both responsible and generous.  

What I see displayed in the Catholic blogosphere and discussion boards is a lack of charity amongst the respective smaller or larger sized families.  Those with smaller families sometimes deride their large family counterparts as freakishly irresponsible.  Those with larger families sometimes deride their smaller family counterparts as selfish.  Both sides forget that selfish/generous and responsible/rash will display differently depending on the individuals involved and their personal circumstances, of which most of us have very limited knowledge at best.

Let's play nice, kiddywinks.  

(Thanks and credit go to Professor Kevin Miller of Franciscan University for the translation points.)