BEYOND BOTTLES, DIAPERS : MOMS DEVISE A MANUAL FOR DAILY BABY MAINTENANCE.

Byline: Elizabeth M. Cosin Daily News Staff Writer

Here's the problem: It's late at night, the baby is crying, yet all of her obvious needs have been met. It doesn't seem serious enough to wake the doctor, and your mother isn't home.

What does a parent do?

Authors Laurie Waldstein and Leslie Zinberg have come up with a solution for all those who realize nine months too late that babies don't come with instruction manuals. ``The Pink and Blue Baby Pages,'' (Contemporary Books; $12.95) is a layman's guide to child rearing, covering everything from how to make your own baby food to how to pack a bag for a day trip or plane ride.

``We tried to put in all the basics, the things parents really need to know,'' said Waldstein, who raised two sons in Los Angeles. ``I'm not slamming the other books out there, but there's such a thing as having too much information. Like they say, too much knowledge can be a dangerous thing.''

Waldstein knew this first-hand from stories she heard from her husband, Peter, who is a pediatrician in Beverly Hills. He often would get middle-of-the-night phone calls from anxious parents who turned out to be worrying over nothing.

It wasn't surprising, then, that friends would call Waldstein for advice, but Zinberg got her share of calls, too, from parents who wanted her recipes for homemade baby food.

The concept of the book began when both women were raising small children of their own. They met at their sons' early-learning school 13 years ago and have been best friends every since.

Their eldest sons are now off to college. The book took almost as long to get published.

The response, however, has been beyond expectations. The authors were told it would be considered successful if they sold 10,000 copies. The number is now 40,000 and growing.

``It took us a long time to get publishers to understand the concept,'' said Zinberg, also the mother of two boys. ``It was a learning process. Now people come up to us all the time and say they can't live without it.''

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Photo: ``We tried to put in all the basics, the things pare nts really need to know,'' says Laurie Waldstein, right, with Leslie Zinberg, her co-author on ``The Pink and Blue Baby Pages.''

John McCoy/Daily News