DAVID SHOBIN is a doctor and author of The Unborn, one of the better examples of the "monstrous baby" subgenre of medical/suspense/horror novels of the last few years. As the title of his second novel, The Seeding, implies, he has attempted once again to use this same fertile territory, but this time he does so with notably less success.

Doctors who write horror and suspense novels are often the envy of their literary colleagues, since they have access beyond those closed and mysterious doors to the medical laboratories and hospital back rooms, places that seem, to the layman's eye, as ominous and fascinating as the inside of the shaman's tent. When Shobin writes of this world, peopled by intense young doctors dedicated to their work, his story is tense and often compelling. He knows these scenes, the knowledge shows, he uses it to good dramatic effect, and we begin to get involved with the lives of his characters and the forensic problems they face.

That problem is a mysterious outbreak of a cancer- like disease in Washington that seems to attack only young pregnant women shortly before they are due to deliver . . . except that sometimes it attacks an infant and sometimes a man, even a doctor, as well. And there is a mysterious figure lurking in the shadows and watching our heroine. And there is the strange and rare orchid that was sent to the famous doctor. And there is the odd coincidence that our heroine just happens to recognize a face in a 150-year-old photo. And the other coincidence. And the other coincidence.

Shobin's characters are reasonably interesting, but they are adrift in a muddled plot whose engine is contrived openly for the novelist's convenience and not for the reader's pleasure. And the ending is pure grade-B movie.

This is a novel only for credulous readers who, as medical patients, believe everything their doctor tells them.