An estimated 100,000 women die every year in the developing world from the consequences of illegal or unsafe abortions in large part because abortion is one of the most common methods of birth control, according to a new report from the Population Crisis Committee.

In a survey made public yesterday, the PCC said that the 28 million abortions that occur every year in underdeveloped countries often result from "inadequate birth control services." The PCC promotes voluntary family planning throughout the world.

The study surveyed 110 countries and graded them according to the availability of birth control pills, intrauterine devices, sterilization (both male and female), safe abortion, condoms, services for the poor, services for minors, sex education in schools and advertising.

The best developed countries were judged to be the United Kingdom, West Germany, France, Italy, Australia, Canada and the United States. The U.S., however, was criticized because of "deficiencies in sex education and contraceptive services for minors" and spotty access to family planning.

In the developing world, only Taiwan, Singapore, South Korea China and Hong Kong were adjudged "excellent." Eighty of the 95 countries surveyed were ranked fair, poor or very poor.

According to Dr. J. Joseph Speidel, PCC president, "The Reagan administration is extending its domestic attack on legal abortion to family planning services overseas" even though "the best way to prevent abortion is family planning."