DES MOINES, Iowa (AP) _ A couple engaged in a week-old ''Breeders Cup'' race with other couples to conceive a child said Monday they were expecting a baby.

A doctor on Monday confirmed the positive results of a home pregnancy test that showed James and Lisa Machamer would be parents, said Scott Schubert, sales manager for radio station KRNQ, which sponsored the race.

The station will award the couple a $1,000 savings bond, a crib and six months of a diaper service.

''I was shocked, excited,'' said Mrs. Machamer, 22. ''But we've been trying for a while. I don't think the contest made any difference; we didn't do anything different. That's the first question everybody wants to know.''

The Machamers, of Des Moines, were among about 20 married couples without children who responded to the station's invitation to participate in the ''Breeder's Cup'' promotion. Of those, three couples were chosen by lot for the race that began a week ago.

Although contestants talked on the radio about their efforts to conceive, the station didn't get any complaints, Schubert said. ''If it's done with taste, you can do it,'' he said.

Mrs. Machamer said she didn't know if she would participate again in a promotion that revealed so much about her private life.

''I was on the radio this morning, we're going to be on the radio in Peoria this afternoon, somebody from Scotland is going to call, it was just a lot of publicity,'' she said.

Still, the mother-to-be said she didn't do too much talking on the radio.

''I didn't say much,'' Mrs. Machamer. ''It was a little embarrassing.''