It’s actually a misconception that the Church advises against the use of fertility drugs. The Church teaches that union and procreation are the twin purposes of sexual intimacy, and that sexual relations are reserved to a man and woman united in the sacramental bond of marriage. In evaluating a drug or technology, the question to ask is whether it helps a married couple to be united with one another and open to the gift of life, or, alternately, if it diminishes or bypasses that union or closes the couple to the gift of life.
Thus in Catholic teaching, the use of fertility drugs that stimulate ovulation is in fact permitted; these drugs can increase the possibility of a pregnancy resulting from normal marital intercourse. However, couples should carefully consider how they will respond to the serious health risks for mother and children if a large multiple pregnancy ensues. Catholic teaching also allows for the use of erectile dysfunction drugs by a married man to make it possible for him to have sexual intercourse with his wife. Under these circumstances, the drug helps the couple who desires to express the unitive and procreative aspects of sexual intimacy. There is nothing counter to Catholic teaching in that desire.
from Neela Kale and the Busted Halo Question Box