Baby boys are not wanted here--not statistically, at least.

In a stunning repudiation of the traditional Asian values that for centuries have put a premium on producing male heirs, surveys show that up to 75 percent of young Japanese parents now prefer baby girls.

Daughters are seen as cuter, easier to handle, more emotionally accessible and, ever more important in this swiftly aging society, more likely to look after their elderly parents.

Plenty of Japanese are dubious about whether the current crop of female infants will grow up to fulfill such parental hopes. Nevertheless, a passion for baby girls has spawned hot-selling books and magazines, pricey sex-selection advice services and clinics that dispense suppository jelly--pink to help produce girls or green for boys--for would-be parents trying to conceive the child of their dreams.

"Boys don't listen and are harder to raise," said Yumi Yamaguchi, 27. To improve her odds of conceiving a girl, Yamaguchi scrupulously followed the advice in a popular sex-selection book and took her temperature for an entire year before trying to become pregnant. She sobbed with joy when her daughter, Ami, was born 14 months ago.

"Boys and their mothers seem to have a weak bond, but mothers and daughters stay close all of their lives," she said.

Yamaguchi lives in a tiny, two-room apartment in Isehara, 30 miles southwest of Tokyo. Her husband and his family run a lumber company. Twenty years ago, such couples usually hoped for a boy to carry on the family business and were likely to keep trying until they got one. But Yamaguchi says she and her husband can't afford a second child, and even if their economic prospects improve, they will try for another girl.

Shiro Sugiyama, chairman of the Sex Selection Study Association of Japan, which has 800 obstetricians as members, estimates that only 2 percent of Japanese women trying to conceive are taking measures to select the baby's gender. Only their thermometers know for sure how many women are really trying, because many, like Yamaguchi, do not consult doctors.

So far, there has been no measurable change in the sex ratio of Japanese newborns. That may be explained in part by the fact that sex-selective abortion is unheard of in Japan, doctors and sociologists say. Although abortion is legal until the 22nd week of pregnancy, the Japan Society of Obstetrics and Gynecology forbids its doctors to reveal a baby's gender before then because of concerns about sex-targeted abortions.

Demographers are concerned about whether and how quickly the boy-to-girl birth ratio could change as Japan's anemic birthrates fall farther and the technology for sex selection grows more reliable, cheaper and, to many people, less morally troubling than abortion.

Sugiyama, whose how-to books on sex selection have sold more than 465,000 copies in the past six years, claims that his method is about 80 percent effective. It is based on such low-tech techniques as charting the ovulation cycle by measuring body temperature, as well as the use of a pH-altering jelly that favors survival of particular sperm cells.

A majority of Japanese men still prefer to have a son if it is to be an only child, but most want one child of each sex, one study showed. This has led some observers to conclude that the women's yen for girls might not translate into more female births, as many men might not cooperate--in the bedroom or the doctor's office--with the sex-selection regimen chosen by their wives.

Whether the current craze produces more females, experts say it is noteworthy as an indicator of a profound social change that includes a weakening of the ancestral male-dominated family system; increasing individualism; the much improved socioeconomic status of women; and a national pension system that makes male offspring less essential to the financial support of elderly parents.

But some people say more couples want girls because life is no longer sweet for Japanese boys. To hear them tell it, hapless male tots are condemned to endure the take-no-prisoners Japanese educational system, followed by a life sentence as a faceless drone for Japan Inc.

"It's tough to be a man," Yukiko Nakayama, deputy editor of My Baby magazine, said with a laugh. "Even when they are little, boys have to compete. If they are bad at sports, it's a problem; if they are bad in school, it's a problem. They have to get into a good university and get a good job. There's a lot more pressure on them.

"Life is easier for girls," concluded Nakayama, who is the mother of a son and a daughter. "They have more choices."

And although Japanese society might give more choices to its daughters, expectations for sons have not been eased. "Mothers feel pressure to raise these boys as they always did: 'Become a good man,' " Nakayama said. "Of course, these pressures existed in the past, but then men had special privileges. Now the privileges are gone, but they still have all the responsibilities."

However tarnished their cachet or prospects, Japanese baby boys are not likely to be outnumbered by girls in the near future, if ever, said Kenji Hayashi of Japan's National Institute for Public Health.

Japan is only beginning to grapple with the ethical issues raised by the emerging sex-selection technology, and the reaction of the medical establishment thus far is to move slowly. In 1994, the powerful obstetrics society, citing safety concerns, issued an edict against using the most potent new sex-selection technique, which involves separating sperm containing the heavier X chromosomes, which produce girls, from that bearing the lighter Y chromosomes, which produce boys. Artificial insemination or in vitro fertilization can follow.

The head of the obstetrics society's ethics committee, Seichiro Fujimoto, said the organization's decision that sperm separation should not be used for sex selection is based on safety concerns and ethical objections. "The general feeling is that it goes against God's logic," Fujimoto said in a telephone interview from Hokkaido University Hospital. "The silent majority, most Japanese, would be against it."

However Fujimoto conceded that this traditional view of nature and ethics holds less sway with the younger generation. Yumi Yamaguchi, the 27-year-old mother, said that authorities should mind their own business. If parents did not have to gamble on their baby's sex, she said, they might decide to have more children--something the government desires.

"They should leave it up to individuals to decide such things," she said as she crawled across her apartment's tatami mats mopping up a trail of Ami's spilled juice. "It's about to be the 21st century, after all."

CAPTION: Yumi Yamaguchi, with her 14-month-old daughter, Ami, followed the advice of a popular book to aid her chances of giving birth to a girl. The number of couples who say they would prefer to raise daughters is on the rise in Japan.