A U.N. survey of 152 countries has found that the United States is one of only six that does not have a national policy requiring paid maternity leave.

Such disparate countries as the Sudan, Cameroon and Nepal, for example, mandate that a woman receive her salary while she is caring for her newborn. The majority of countries surveyed provide benefits through social welfare systems, some require the employer to pay and still others combine both financing sources.Only the United States, Australia, New Zealand, Lesotho, Swaziland and Papua New Guinea do not require paid leave, according to the review of International Labor Organization member countries.

The 114-page study, "Maternity Protection at Work," is being issued on Monday. It was undertaken, its authors said, because of the importance of women's salary for family survival.

The study found that women contribute half or more of family income in about 30 percent of households in the nations studied. In the United States, the figure is 55 percent, and in Europe, 59 percent.

The agency estimated that by 2010, the figure for women who work during their childbearing years in industrialized countries would rise to about 81 percent, from the current 73 percent. In less-developed regions, the study indicated, the figure would rise to 68 percent from 63 percent.

While rights are written into law in many countries, all is not rosy for women worldwide, said one of the study's authors, Ann Herbert. "There is a huge gap between law and practice," she said, adding that widespread discrimination was found to exist on the job against women who become pregnant.

The study found that only 29 countries, most of them in Africa and Asia, absolutely bar dismissal of a worker during her maternity leave. There is even less protection against dismissal after the mother's return to work. About two dozen countries have some protection, but it ranges from 30 days in Belgium and South Korea to 15 months in Mali and Senegal.