Among married men and women who undergo surgical sterilization through a vasectomy or a tubal ligation, it has been estimated that anywhere from ten to twenty percent will come to regret the choice. Sometimes there may be an immediate awareness of wrongdoing following the surgery, while in other cases, as Patrick Coffin, radio host and author of ''Sex au Naturel'' notes, sterilized couples may "...drift for years before acknowledging that something between them is no longer in sync. After the initial pregnancy fear subsides, and the vision of 1001 erotic nights turns out be something of a scam, spouse may (subtly) turn against spouse while doing their best to ignore the silent, disturbing 'presence' of the choice they made."

Their decision to seek out a permanent form of contraception can also affect their marriage in other important ways. As Dr. John Billings has noted: there is "an effect that is even more tragic than the clinical and it is that in many cases the use of contraceptive methods in marriage has been followed by an act of infidelity of one of the members. It would seem that contraception diminishes the mutual respect of husband and wife... Additionally, the abandoning of self-control diminishes the capacity to exercise this self-dominion outside the marriage."

The "abandonment of self-control" that can follow permanent sterilization raises ongoing spiritual and moral challenges for couples who later repent and confess the sin of having undergone a vasectomy or a tubal ligation. A unique and vexing problem arises because sterilized individuals may find themselves, as Patrick Coffin observes, "sorely tempted to delight in the very sex-without-babies mentality that led to the sterilization in the first place."

Repentant couples, out of an abundance of spiritual caution, may thus wonder what they should do, and whether they are obliged to get a surgical reversal of the procedure. The Church has never declared this to be a required step, in part because of the risks and burdens associated with surgical interventions, in part because of the high uncertainty of a successful outcome, and in part because of the potentially significant expenses involved.

Even though a reversal may not be feasible or obligatory, the repentant couple may nonetheless become aware of the need to order their sexual activity and appetites in the face of their original sterilization decision and its extended consequences. They may recognize a pressing interior need to grow in the virtue of marital chastity and to engage in a lifestyle that authentically embodies their new, albeit delayed, rejection of the contraceptive mentality.

In these situations, clergy and spiritual advisors will often encourage couples to pattern their sex life on the same cycle of periodic abstinence that fertile couples follow when using Natural Family Planning (NFP). During times of abstinence, the couples actively exercise self-control, thereby reordering the sensual and sexual appetites. This strengthens spouses in their resolve not to reduce each other to objects for pursuing sexual self-gratification. This is important because various forms of contraception, including permanent sterilization, often involve the phenomenon of the woman feeling as if she is being "used" by her husband.

Abstinence, therefore, assists couples in learning to express their mutual love in other ways. Pope John Paul II explains this perspective in his famous work ''Love and Responsibility:'' "Inherent in the essential character of continence as a virtue is the conviction that the love of man and woman loses nothing as a result of temporary abstention from erotic experiences, but on the contrary gains: the personal union takes deeper root, grounded as it is above all in the affirmation of the value of the person and not just in sexual attachment." In one of his weekly general audiences later as Pope, he further notes that "...continence itself is a definite and permanent moral attitude; it is a virtue, and therefore, the whole line of conduct guided by it acquires a virtuous character."

Fertile couples who incorporate NFP into their marriages to avoid a conception often end up acquiring a different attitude towards life as they chart and practice periodic abstinence: they can have a change of heart and discern a call to have one or several additional children. A similar spiritual conversion to a culture of life might reasonably be expected to occur among some sterilized couples who resolve to live out an NFP lifestyle, perhaps becoming more open to adopting a child, or more open to other forms of spiritual parenthood in their communities such as Big Brother/Big Sister programs.

By abstaining during fertile times, then, the sterilized couple reintegrates the same positive behaviors that they might have practiced had they not chosen to be sterilized. In this way, the science of NFP offers the repentant sterilized couple a school of opportunity to acquire virtue within their marriage and their conjugal relations.

Father Tadeusz Pacholczyk, Ph.D. earned his doctorate in neuroscience from Yale and did post-doctoral work at Harvard. He is a priest of the diocese of Fall River, and serves as the Director of Education at The National Catholic Bioethics Center in Philadelphia. See www.ncbcenter.org.