THE ABORTION PILL, by Etienne-Emile Baulieu with Mort Rosenblum (Simon & Schuster: $22; 186 pp.). This slender volume is sure to heat up a long-simmering debate, particularly as Roe v. Wade hangs in such precarious balance. Baulieu is the man who discovered RU-486, which he calls, in his subtitle, "A Woman's Choice," though his anti-abortion foes consider it pharmacological evil incarnate. RU-486, in a single dosage, will induce abortion without any of the risks that accompany invasive procedures like suction. To hear his opponents tell it, RU-486 also will breed a generation of irresponsible women who blithely pop a pill to destroy human life with as little thought as they give to taking an aspirin to kill a headache. This book is the story of the politics surrounding the pill's release worldwide, as well as an argument for its acceptance. It is informed by a world view that moralizing politicians sometimes tend to forget. "If we are to have the enlightened future Margaret Sanger foresaw half a century ago," writes Baulieu, "women must be free to control their own bodies. Parents must be free to shape their families, so that children will be born to mothers prepared to raise them. A stabilized world population could then sustain itself."