His new project, ''Bachelor's Baby,'' reflects his real life love with Chelsea Field

Scott Bakula knows from quantum leaps. He jumped from Broadway song-and-dance man to prime-time star when he landed the part of time traveler Sam Beckett on the 1989-93 series Quantum Leap. Now he’s adding ”executive producer” to his resume, with his new CBS series, Mr. & Mrs. Smith (a Thin Man-meets-The Avengers spy series costarring Maria Bello), and The Bachelor’s Baby, a CBS movie about a single guy faced with fatherhood after a romantic fling (Sept. 29). The latter is less of a leap in that it stars Bakula and real-life love Chelsea Field, who gave birth to their son, Wil, shortly before shooting began.

Is the movie inspired by actual events? ”There are certain aspects of the movie that do parallel our life together,” admits Bakula. ”I’m having a nervous breakdown. That’s how it mirrors my life,” laughs Field, a typically harried first-time mother. ”I played her as a woman who had one too many things piled on top of her, and it broke her. I can see how that could happen,” adds the actress, who also started as a hoofer (including two years as a Solid Gold dancer) before turning to acting full-time in films (Flipper) and TV (the short-lived Nightingales). ”For Bachelor’s,” she says, ”they had to paint dark circles under my eyes. They wouldn’t have to now.”

Bakula agreed to produce and star in the movie-of-the-week because it wasn’t sensational or about a disease. ”It had good human values and it made you laugh. I read it and said, ‘They’re never gonna make this movie.”’ The actor, who has two children (Chelsy, 12, and Cody, 5) with his ex-wife, Krista, met Field in 1993 when they costarred in the feature film A Passion to Kill. The couple have shared a home since November and resisted being interviewed together, until now. ”We wanted to promote [the movie] — and ourselves — because we’re really happy about it,” he says.

Bachelor’s Baby may also mark the last credit for ”Chelsea Field,” since the actress is considering reviving her real last name, Botfield. ”I dropped the ‘Bot’ when I started dancing, but since we have no plans to marry, I wanted to go back to Botfield to have more of a connection with my son,” explains Field — uh, Botfield. ”But I’m realizing more people know who I am than I thought, so maybe it’s not the smartest thing to do. It’s not quite solved yet, and people are confused.”

So, apparently, is Bakula. ”I’m glad you’re asking these questions,” he tells this interviewer, ”because I wanted to know the answer.”