ABORTION AND THE BORDER. Mexicans go north for abortions. Subject is so taboo that few talk about it and statistics are scarce

US Immigration stamps a visa in her Mexican passport. She flashes it at the US border guard and slips it into her purse. Magdalena Bustamante (not her real name) is on her way north. Pregnant, she is en route to the nearest United States abortion clinic. In Mexico, abortion is illegal. For generations, American women fled to Mexico for clandestine illegal abortions. But in 1973 the US Supreme Court's landmark Roe v. Wade decision triggered a historic reversal. Now, even as ``pro-lifers'' here struggle to reverse the law, thousands of Mexican women journey north for legal abortions.

``I couldn't stand to make a Mexican abortion,'' says the pretty 28-year-old after she and her boyfriend crossed the border at Nogales on their way to the Womens' Surgical Center, an abortion clinic in Tucson, 60 miles north.

``In Mexico it's clandestine, sordid,'' she says. ``Most doctors are very negative. They make you feel guilty, like you have sinned. For many, it is just a business.''

The women who come to US abortion clinics are the ones who can afford it, despite a plummeting peso. Abortions here cost an average of $225 plus travel expenses.

The vast majority of the 1 million to 2 million women who have illegal abortions each year in Mexico can't afford to come to the US. Instead, they pay underground Mexican doctors and untrained midwives to perform the procedure. The poorest of the country's 20 million women of childbearing age induce abortions on their own. At that level, abortion, colloquially referred to as espanta ciguena (``to scare off the stork''), reverts to dangerous folk remedies.

Two hours later, in Tucson, Magdalena is one of three Mexican women patiently listening to piped-in disco music in comfortable black vinyl and chrome chairs. She is pleased with how gentle and open the nurses and doctors are during her visit, but surprised to see placard-carrying pro-lifers demonstrating outside.

Magdalena is among a minimum of 300 Mexican women who come each year to Women's Surgical, one of 10 similarly priced locations offering abortions in Tucson, estimates clinic physician Scott Ricke. The number of Mexican women, he says, has remained constant in spite of the devaluation of the peso.

But no one knows exactly how many Mexican women come across the 1,900 mile US-Mexican border for abortions each year, says Tucson Planned Parenthood executive director Dan Topp.``Nationality is something we do not ask,'' he explained.

Despite its prevalence in fervently Catholic Mexico, los abortos are what Magdalena's boyfriend calls an ``underwater subject.'' It is so taboo that few statistics are available and most people, even doctors, are reluctant to discuss it.

Nevertheless, no one denies that illegal abortions are a serious and mushrooming problem that may kill as many as 140,000 Mexican women a year, according to journalist Alan Riding in his 1986 edition of ``Distant Neighbors,'' a book on Mexico.

``The danger of mortality comes because abortion is clandestine,'' says Dr. Manuel Mateos Candano, a Mexico City gynecologist who is one of Mexico's most vocal proponents of legalized abortion. ``Women go to places where professionals are not in charge,'' he says.

Mexican abortion law dates back to Jan. 2, 1931, says Diana Vivarte, a founder of CONAPO, the National Council on Population, the government agency responsible for demographic planning. Under the law, abortion is legal only in cases of rape or when the mother's life is endangered.

Since 1936, there have been efforts from within and without the government to bring about a change. The latest push to legalize abortion was in 1983 when CONAPO proposed to the Mexican National Assembly that abortions be depenalized and provided free for women who want them. The referendum was killed before it reached a nationwide vote.

Standing in the way of legalization are the church and right-to-life groups like the well-organized, Catholic-backed pro-vida, say abortion proponents.

``We have a lot of pressure from those groups,'' says Dr. Anameli Monroy de Velasco, a Mexico City psychologist who is a director of an independent research and counseling center for teen-agers. ``If the US, a developed country, has pressure from pro-lifers, imagine what it is like here in a country where Catholicism is preponderant.''

Many Mexican gynecologists are also resistant to changing the law.

``I'm opposed to abortion as an aggression to a living being that can't defend itself and represents taking life away while a doctor is made to give life,'' says Manuel Suarez Cobo a former vice-president of the Mexican Gynecologist Association.

Despite church opposition, the government and most health professionals support family planning. And 48 percent of Mexican women use some type of birth control, says Dr. Mateos. As a result, the birthrate has steadily declined in recent years.

But birth control, like abortion, faces another obstacle: the traditionally patriarchal family structure in Mexico in which women, particularly those in the lower classes, are tied to the family by having children. ``The `machismo' factor is real. Men here like to have their women pregnant,'' says Dr. Monroy.

Those who favor abortion say a strong, united womens' movement is necessary before abortion can be legalized. Although there are many small feminist groups, no such movement exists, says Mexican feminist Teresa Leal. And abortion appears to be low on the list of feminist priorities.

``In comparison to other problems we face, abortion is a luxury problem,'' she says. ``Remember, women here were just granted the right to vote in 1953.''

Back in Tucson, Magdalena prepares to leave the clinic after her abortion. She is pessimistic as to whether abortion become legal. ``The trend in church and society in Mexico is toward conservatism,'' she sighs. Weary, she walks past the American pro-life demonstrators to the car.