Between 1970 and 1984, there was a 300 percent increase in the number of women maintaining single-parent homes, and a 300 percent increase in the number of college-educated women becoming single parents.

These findings from the Census Bureau are among the most significant changes in American family life that have been analyzed in a new book, "The Divorce Revolution, the Unexpected Social and Economic Consequences for Women and Children in America," by Lenore J. Weitzman, associate professor of sociology at Stanford University. What has happened, she says, "is the impoverishment of middle-class women and children."

Weitzman's 10-year study of the effects of no-fault divorce in California was instrumental in persuading Congress to enact the new Child Enforcement Support Act of 1984, which requires states to implement procedures for mandatory withholding from wages of parents who do not pay court-ordered child support.

She found, for example, that within a year of divorce the women's standard of living dropped 73 percent while that of the men rose 42 percent. Unrealistic property division was one important factor. Others include low awards of child support and lack of enforcement of payments, termination of child support at the age of 18, and abandonment by the courts of alimony.

A comparison of child support awards showed that in a number of California counties, the average awards were less than the cost of day care for two children and less than they would receive if they were on welfare, said Weitzman. "As a result of my research, California passed a law that child support cannot be less than welfare. For kids growing up in middle-class families that's an absurd standard."

In most states, child support stops when the child turns 18, "just at the point where kids are going to college. That's an incredible economic burden for a woman to bear alone." Weitzman recommends changes in state laws to require parental support to continue for full-time students until they finish their education. While this can be done voluntarily by individual couples, she said, "the mother who is concerned about this often has to give up something else."

The new federal law to enforce child support has drawn attention to the fact that 53 percent of absent fathers do not comply with court-ordered child support. Weitzman's study of men with earnings between $30,000 and $50,000 a year found that "they are just as likely not to comply with court orders as men who earn less than $10,000. For them to have the same record of noncompliance suggests it's not the ability to pay but lack of enforcement. They know the system in the past has made it optional."

Women who received alimony in the past are not receiving it under no-fault divorce. "The new assumption is those wives can go out and support themselves. Eighty-five percent are not receiving a single penny," Weitzman said.

Of women married more than 18 years, a third are receiving no alimony. "For those who are it's the equivalent of $350 in 1984 dollars. It's a very minimal amount and it lasts for an average of 24 months. You tell a woman who is 55, you've got $350 [a month] for two years and that's it, with no career history, this is really cruel."

Weitzman began her study of no-fault divorce, thinking it was a sensible approach and that it would remove the abuses that existed under the old system when only the innocent spouse could file for divorce. She also saw it as a law that treated women equally in a marital partnership. "In most situations it was the husband who wanted the divorce. He had to buy it from her because he needed her cooperation. That was her lever. Under no-fault she's lost her bargaining chips.

"The result is that women have been unequally disadvantaged by divorce," she writes. And it has hit women with younger children and older homemakers hardest. In her book, she recommends a series of legislative and judicial reforms designed to equalize the standard of living in the custodial and noncustodial households and to protect older homemakers and custodial parents from the loss of the family home.

Tougher laws to enforce child support are being implemented throughout the country, but they will solve only a portion of the problem. States are being required to establish commissions to examine the effects of divorce and to establish guidelines for child support. The Weitzman study and her recommendations should be required reading for every commissioner. And perhaps the new reforms won't wreak the economic devastation that the last round did.