BABY TALK. To be or not to be parents is the fertile subject matter of "Baby," a winning and often wise musical at the Olney Theater. This is real "family" entertainment.

Briskly directed by David Saint, and performed by an attractive cast on a clever turntable set, "Baby" revolves around the reactions of three college-town couples to news of their impending and unplanned parenthood.

Young student/musicians Danny and Lizzie have been working hard at keeping their unconventional (and unmarried) status. With the last of the kids moved out, affluent Alan and Arlene had planned a "life begins at 40" rediscovery of each other. And would-be comic Nick and tomboyish Pam, a pair of likable jocks, have long been trying without success to have children.

The three women meet in the waiting room, and in the exuberant "I Want It All," announce their great expectations for themselves and their children. Their men are challenged and excited by the daunting prospect of being husband and father. As Alan observes, "Any woman worth loving these days is gonna be complicated -- they want it all."

But as anyone who has done it will tell you, having a child is not all sun and fun, and "Baby" is peppered with twinges of truth. Emotions shift suddenly from surprise to apprehension to elation and back again, and transformations occur even before the babies arrive. Arlene, fretful and unsure about having another child, is afraid she's only been a mother, not a wife. Lizzie is afraid she'll lose her independence, and gets laughs when she pronounces that "you have to fit the baby into your life. And she's inundated with advice from women eager to share the pleasures and pains of their pregnancies. And Nick and Pam, told their pregnancy was a false alarm, endure the romance-reducing rigors of "sex by the book," as they follow doctor's orders for another attempt.

David Shire's jittery pop score, nimbly conducted by Rob Bowman, has the chipper insistence of commercial jingles, and the lyrics by Richard Maltby Jr. and the book by Sybille Pearson are consistently clever. As in "A Chorus Line," these songs seem to have sprung from real experience.

The Olney cast is uniformly excellent, but Joy Franz and Romain Fruge stand out as the complex Arlene and irrepressibly animated Danny. Carole Lehan's casual choreography works well within James D. Waring's effectively spare set and lighting.

This "Baby" makes having little ones look mighty attractive. But even if the show doesn't set off another population explosion, it's safe to say there will be a "Baby" boom at the Olney Theater's box office.