AS THE FIRST FEMALE to win the Kentucky Derby in 65 years, Genuine Risk may well be the big name in sports this spring. But it's going to cost her. She is certainly going to lose her privacy. Her sex life is already a matter of public speculation. Already, she's been accused of having what in polite human company is called Female Trouble. In horse racing it's called, appropriately enough, horsing. And we're going to be hearing a lot about it.

There are, of course, differences in the way female people and female horses manifest this phase of the reproductive process. New York track veterinarian Manuel A. Gilman says that fillies and mares in training, like many female athletes, often don't have a regular cycle. Those that do usually aren't bothered by it. "Once in a while you'll get one who gets cramps and can't run, but in most cases it doesn't bother them," any more than the reproductive process bothers the stallions who are in training. "Their mind is on racing."

Genuine Risk has had female trouble. Her trainer, Leroy Jolley, blamed one of her weaker races this season on the fact that she was deep into a heat cycle. She went to the lead in a race and promptly lost interest. Her mind, apparently, was on something else. This problem is not unprecedented. In 1953, the filly Nellie Flag was the favorite to win the Kentucky Derby. She finished fourth and her jockey, Eddie Arcaro, blamed her defeat on the fact that she was thinking of other things.

Somehow, when you are female, your sexuality gets blamed for your shortcomings. And sexuality, it should be noted, is not something one can do much to change.

I know a young man whose sexuality is causing him problems. His thoughts have turned to lust this spring and he has had a terrible time concentrating on his work every time he sits down to a typewriter. But you never hear about Male Trouble. What you do hear about is Female Trouble.

A grouchy or irritable woman isn't grouchy or irritable because she didn't get enough sleep or because she has legitimate reasons in her life to be grouchy or unreasonable -- things like having checks bounce, or flat tires, or rotten kids, or not being paid enough for her work. No, women are grouchy and irritable because It's That Time of the Month. Or they have the Curse. Or they've fallen off the roof. Or they're flying baker. (Ask a Navy man.)

I once knew an editor who prided himself on being sensitive to his female reporters' Time of the Month. It was okay for them to be irritable at that time. He understood. At first this sounds like an editor who is a true humanitarian, but in effect what he had there was a handy excuse for dismissing the source of the reporter's irritation. The women weren't arguing with him because he was perhaps wrong; they wer arguing because they were temporarily insane.

But he at least was willing to put up with this crippling condition of women. Other employers were not. Not so long ago, this was one of the serious flaws of women that did them no end of harm in the job market. Employers knew they were headed for real trouble if they hired mothers because mothers invariably had children who invariably got sick, and the mothers invariably had to stay home from work to care for them.

Right alongside the motherhood problem was the other problem: the one that affected all women, the fact that they might be great workers most of the time, but geez, when it came to That Time of the Month, there was no getting through to them. Hiring women was just too much trouble. They'd either go crazy or have to stay home sick at least once a month.

The fact of the matter is that most women wouldn't be caught dead letting anyone, particularly a male colleague, know when it's that time of the month. That would be downright unprofessional. Women purposely avoid playing into the stereotype, and the upshot is you don't hear much about the stereotype anymore.

Until Genuine Risk. Now, we're going to be hearing a lot about it.

American horse racing is about as male dominated as a sport can be. Female horses routinely run against male horses in Europe, but here they are regarded as the weaker sex and they usually run against each other for smaller pots. Even Ruffian, whom some consider to be the greatest filly of the century, ran exclusively against females until the match race with Foolish Pleasure that killed her. It is no accident that the only other female to win a Kentucky Derby was Regret in 1915. The last female even entered was Silver Spoon in 1959. Leroy Jolley is wondering publicly whether Genuine Risk is durable enough to run in both the Preakness and the Belmont.

But the Firestones broke the tradition last weekend and entered their filly against colts in the most popular and famous race in America. Genuine Risk collected $250,000 for her win over colts in the Kentucky Derby and now there is a lot of talk about sending her to the Preakness May 17 or the Belmont in June, or both. This means the betting world will have to consider a whole new factor in handicapping the Triple Crown races: Is Genuine Risk horsing?

Saturday's Derby was a close call. Jolley told a reporter who stopped by his horse's stall on Friday that Genuine Risk was just leaving her cycle. The next day she ran the race of her life. Apparently when she's leaving her cycle, she's back to her usual self. But who knows?

Already turf riders are settling down with their calendars and trying to figure out what phase of her cycle Genuine Rish will be in for the Preakness and the Belmont Stakes. The questions could get wild. Is she regular? Is she cranky? Is she simply lustful or moonie? How long, for heaven's sake, is a horse's cycle?

It is, as Dr. Gilman explained patiently, different from humans. But I'll bet one thing will be the same. If Genuine Risk loses, somebody will say it was That Time of the Month.