I tried to get answers for this question but I did not get an answer from the “Ask an Apologist” forum.
I try to draw the situation again in this thread. The issue is birth control for very serious medical reasons and if the NFP does not work as they should (sorry NFP’s guys, I totally disagree with you about NFP, theoretically the work, but practically depends on the person: I have friends that went trough different courses and learned the symptom-thermal method and have now new unwanted although beloved babies).
We have to remember why contraception is a sin. It is a sin when before, in or after the sexual act the spouses use any kind of mean to render it sterile. It is not a sin to regulate ovulation or the levels of hormones by itself.
The sin is the act itself, not the prevention of ovulation or the regulation of hormones. If a couple make use of the pill to regulate the menstrual cycle and abstain from sex when fecundation would theoretically be possible based on a rhythm method, is that a sin? They have sexual contact only in the phase that by the rhythm method (now regulate tightly) is labeled as infertile, I do not see where the problem is. Yes, they make sure that the infertile phases are really infertile, but this is an indirect consequence of the use of the pill: according to the rhythms method they are already infertile “naturally”.
But if there is a problem with allowing or not ovulation to occur here an alternative method: to regulate the level of hormones (primolut-nor)** ONLY** in the second part of the cycle to assure a constant menstrual cycle, stop taking it to induce the bleeding and abstain from sex when ovulation (now planed) is REALLY occurring around day 14. Where is the moral problem with this method?
Merry Christmas to you all.