Here is what I thought I knew.
The Luteinizing hormone (LH) in the female menstrual cycle precedes ovulation by about a day. It is the pink line with a spike in the graph shown here. If the MAP is taken too soon before the LH surge, it has no effect. If the MAP is taken just before that, it can stop the LH surge and thereby prevent ovulation. If it is taken during or after the surge, it probably will not stop ovulation but it may or may not interfere with implantation of an embryo should the ovum become fertilized by sperm. If it is taken after implantation, it has no effect.
Thus, the MAP is morally illicit for married couples because it is contraception. It is considered by some to be morally licit only 1) in the case of rape, and 2) if it is taken just before the LH surge to prevent ovulation. It is illicit to give it to a rape victim during or after the LH surge because there is a risk that the pill will cause the death of an embryo by inhibiting implantation, which is a chemically-induced abortion. Is that what you thought too?
About the author
Stacy Trasancos, Ph.D. is a wife and mother of seven, raising five children with her husband in the Adirondack Mountains, and laying awake at night worrying about the two grown ones. She is a chemist turned homemaker and joyful convert to Catholicism who is currently pursuing an MA in
Theology at Holy Apostles College and Seminary. She is Chief Editor at Ignitum Today and Catholic Stand, and writes about all that she is learning at Accepting Abundance.