The Pill, when first introduced 17 years ago, seemed the final solution to the problem of unwanted pregnancies. But continuing reports about the Pill's side effects have caused many women, and men as well, to turn instead to a simple, virtually 100 percent effective—and largely irreversible—alternative: sterilization. A close student of the trend is Dr. Charles Westoff, 50, director of Princeton University's Office of Population Research, who has been studying contraception for 12 years as co-director of the government-funded National Fertility Studies. The only child of a Consolidated Edison executive in New York City, Westoff has been interested in demography since his undergraduate days at Syracuse University following service in the Navy. The father of two children by his first marriage, he is now married to Leslie Aldridge Westoff, a freelance writer and author (The Second Time Around: Remarriage in America). The Westoffs collaborated on From Now to Zero—Fertility, Contraception and Abortion in America, which they wrote on their honeymoon in 1969. Recently Westoff talked about the new trend toward sterilization with Richard K. Rein for PEOPLE.

How many Americans are opting for sterilization?

In 1975, the most recent year for which we now have statistics, about 6.8 million married couples of childbearing age used sterilization as their form of contraception, and another 1.1 million persons had been sterilized for medical reasons.

How does this figure compare with couples using the Pill?

About 7.1 million couples were found to be using the Pill. One big change was for couples married five to nine years; 22 percent of those using contraceptive methods had been sterilized—compared to just 8 percent five years before.

How did you obtain your data?

In 1975 we interviewed 3,403 women throughout the country. They represent a national sample of white women below the age of 45 who had been married once to husbands who, for their part, had had only one marriage. We also were able to compare our survey results with the 1973 National Survey of Family Growth, which was based on a sample of women of reproductive age. Thus we could derive estimates of contraceptive usage among all currently married women, white and nonwhite.

Why did your sample not include black women?

We didn't include blacks in this survey because the number of respondents would have been too small to get reliable results. We do know from past surveys that something like 95 percent of sterilizations among blacks involved females. This may be partly because the black woman traditionally has had to accept more responsibility for the control of fertility than her white counterpart.

What trends do you find in the choice of methods of contraception?

By 1975 we found that about 75 percent of all couples using some form of contraception were using one of these methods: sterilization, the Pill or the IUD. But we also found that usage of the Pill had reached a plateau and possibly is beginning to decline. The Pill is still the most popular method, but its supremacy is being challenged by sterilization. We also found that, since 1970, the incidence of sterilization among older couples married 20 to 24 years had doubled.

Did these figures surprise you?

They certainly did! The increase in sterilization between 1973 and 1975 was tremendous. But it did jibe with estimates made through medical records by the Association for Voluntary Sterilization in New York. It's quite consistent.

What are the main forms of sterilization?

For men, the method is vasectomy, tying and cutting the ducts that carry the sperm. It is a simple operation accomplished by small incisions in the scrotum and usually done in a doctor's office under a local anesthetic.

Aren't vasectomies irreversible?

That should be the proper attitude. It depends on how well the vasectomy was done in the first place and on the skill of the surgeon trying to reverse it. In general the chances are poor.

Does sterilization render a man impotent?

No, although there has been some concern, particularly among less educated people, that sterilization implies impotence, which it does not. There may be some psychological consequences, however, where the person initially feels less than whole. But studies that enumerate various consequences conclude that the benefits far outweigh the costs.

What are the choices for women?

There are several relatively simple operations which close off the fallopian tubes. Sometimes, as in a vaginal tubal ligation, entry is made through the vagina itself. Another method of surgery is a laparoscopy, the so-called "Band-Aid" or "belly-button" operation, in which surgery is done through a small incision in or near the navel. Since the patient can leave the hospital the same day, laparoscopy has made sterilization much easier.

Why this dramatic increase in sterilization?

The primary reason is probably the increasing concern about the Pill and its side effects. Sterilization seems to be the method people adopt after they've been using the Pill and have had the number of children they want. They may be in their early 30s and face another 15 or 20 years of exposure to the risk of an unintended pregnancy. The prospect of having to swallow a pill every day for the next 15 years, combined with the reports about side effects, is pretty bleak. I suppose that the incidence of sterilization in this country is a sad commentary on the contraceptive technology available. You have a choice between the Pill and the IUD, both of which have side effects, or reverting to the older, traditional methods, which have higher failure rates.

What kinds of people decide on sterilization?

We do know that vasectomies have appealed somewhat more to men with higher incomes. In lower-income families, more women than men have been sterilized. This is particularly true for poor women who have had a history of unintended pregnancies and who frequently can have the operation done in a clinic. Sterilization is most popular in the American West—perhaps one-third more couples in California, Oregon, Washington and Utah are sterilized. Every survey has indicated that in California sterilization is extremely popular. You might argue that many new styles get started in California, but I don't know for sure what the reason is.

Has women's lib had any impact?

The sheer fact that contraceptive sterilization is almost equally divided between men and women, at least among whites, indicates that the concept of equality in marriage is making inroads. But women still take primary responsibility for contraception.

Would sterilization decrease a woman's desire for sexual intercourse?

No, quite the contrary. There should be less apprehension about getting pregnant unintentionally, and therefore greater receptivity to the idea of sexual activity.

Do couples ever regret sterilization?

If something unpredictable happens to a couple's existing children, that could change their attitude. Or the marriage could break up, and one of the partners might want to remarry and have children.

What are the prospects for another revolution in contraception?

There doesn't seem to be anything radically new on the horizon. There was talk of developing contraceptive vaccines, but this research involves more than is presently known about immunology. There are new generations of the Pill coming along which promise fewer side effects. Work is also being done on the "morning after" pill, which would appeal to a segment of the population whose sexual activity is less predictable. But a great deal of basic research needs to be done before any innovation comparable to the Pill.

What does the current trend toward sterilization indicate?

It tells us that we are rapidly reaching the point where American couples will be having the number of children they want, when they want them. This sort of perfect contraceptive society is still down the road a bit. But the fact that 75 percent of couples using contraception are choosing from among the three most effective methods of birth control means that we are getting close to it.