Three recent trends in the auto industry have combined to create a fourth that carmakers are just beginning to track: the growing attractiveness of trucks to women.

These are not the large 18-wheeler semis that appear in highway drivers' rear-view mirrors just in time to warn them to scoot their cars out of the way. Instead, women are drawn to the smaller trucks, such as pickups, vans, minivans, and sport utility vehicles popularized by Jeep.Light trucks, as they are called, account for 95 percent of all U.S. truck sales. They have been taking an increasing share of the overall vehicle market, rising to about 31 percent in 1987.

Volume as well as share has been high in that market. Last year, about 4.7 million small trucks found new homes, many of them driven away from dealerships in place of cars. One reason for the migration may be that trucks offer carlike rides and comfort.

That is the first trend. The second is the movement of women into the car market. Last year, 44 percent of principal owners of new cars were female, compared with 36 percent in 1980.

The third trend is the decade-long overall reduction of car sizes. Mirroring that development has been the introduction of compact pickup trucks, like those from Mazda, Nissan and Toyota.

"Compact trucks were the turning point of moving women into the market as high-volume truck buyers," said Louis E. Lataif, head of Ford Motor Co.'s North American sales operations.

Lataif, whose company has been tracking women in the truck market for two years, noted that besides their smaller sizes, trucks became more appealing through carlike features such as air conditioning, stereo radios and other comforts.

Those trends have combined to boost truck sales to women. Last year, women purchased an estimated 755,000 such vehicles and accounted for 17 percent of the light truck market, compared with 15 percent in 1986.

Compact vans, or minivans, have largely been credited with attracting women to the truck market. Introduced by Chrysler Corp. in the mid-1980s, minivans now have the highest percentage and volume of women buyers.

Among the more popular makes, 35 percent of the buyers of Chrysler's Plymouth Voyager are women, according to Maritz Marketing, a Toledo, Ohio, research firm. Ford's Aerostar has a women-buyers' rate of 32 percent, which is the norm for this segment, while Chevrolet's Astro and Safari vans are 29 percent, probably because they are more popular in their commercial versions than the Ford and Chrysler models.

"Women use the small vans for shopping and for car-pooling children," Lataif said. "The small vans are also maneuverable and comfortable enough to drive to work every day."