So now, the United Nations says, we are to have the "International Year of the Child." It's not a year too soon, considering the generally sad plight of millions of children in most parts of the world, including the United States.

Americans have long cultivated the national myth that our country is a child's paradise. But one specialist in the field, Albert Rosenfeld, asks, "Do we really give a damn about children at all in this society?"

Well, of course we do, but there are other countries that care more. The United States does, however, know how to put on a good show: One way or another we always are having a Year of the Child, the most spectacular version being the celebrated 1970 White House Conference on Children and Youth, which promised much and produced little.

It did for a time, though, generate so much momentum that Congress in 1971 passed an impressive Child Development Act - which came to nothing when President Nixon vetoed it.

Two years later, on October 13, 1973, Nixon staged another public-relations program, this time calling it "Child Health Day." The Citizens Committee for Children in New York scorned it as "a poor substitute for action."

Nixon's successor, Gerald Ford, took up where he left off. Ford in 1975 vetoed the Child Nutrition Act, the best bill of its kind ever passed by Congress, on th ground that it would cost too much (it would have come to less than $3 billion).

It's not clear yet what can be expected of the Carter administration, although it is encouraging to note that the new President has appointed officials like Joseph Califano, the Secretary of Health, Education and Welfare, who is known for his interest in social programs.

Carter and Califano, partly in an effort to find alternatives to abortion, are toying with a new plan to cope with the nations's orphans. Both are against abortions on principle and oppose Medicaid-subsidized abortions for women who can't afford to pay for them.

There are already hundreds fo thousands of orphans in the United States, but the effect of the Carter-Califano plan would seem likely to increase, rather than reduce, the total, for if the pregnant poor are now forced to bear children against their will, the ranks of the unwanted offspring would be swelled by many thousands every year. Medicaid abortions exceed 300,000 annually, and the total is constantly increasing.

What's to become of the children whose mothers can't look after them, and who, for one reason or another, are hard to place? Under the administration plan, the government would provide subsidies to families that are willing to adopt them. This could amount to several thousand dollars a year to each family as long as the adopted child was dependent. Obviously, the cost could far surpass that of subsidized abortions.

Only a few months ago the adoption idea was opposed by the administration on the ground that it was too expensive. Nevertheless, Califano is now on solid ground when he finds that existing government policy "doesn't make any sense."

Currently, the U.S. spends about $170 million a year in welfare payments for children in institutions or foster homes. The payments are cut off, however, if the children are adopted. Califano believes one of the main reasons orphans are not adopted is that the families cannot afford the high cost of medical treatment, special education and rehabilitation that many require.

Perhaps the most surprising part of the administration plan is it support of a provision that would guarantee medical expenses for pregnant women who agree to put their babies up for adoption after birth. That comes close to a bonus for producing orphans.

It remains to be seen how the Carter administration is going to tackle the larger problem of raising America's standards of child care in general. The United States, for instance, still ranks behind 14 other nations in preventing infant mortality. About one-fifth of American children get little or none of the medical care they need. Countless children go to bed and to school hungry.

European health systems provide preventive services, such as specialized nursing care, along with much home visiting to educate, examine and immunize. Europeans have found that if a child-health program is geared for the poor alone it rapidly becomes a poor system. Hence, all children are eligible and all are covered.

When the International Year of the Child gets under way, attention should be particularly directed at the dangerously low levels of immunization that are causing or threatening epidemics of preventable diseases throughout the world.

Only around 65 per cent of American children under 14 are adequately protected against polio, diphtheria and other common infectious diseases. In the first three months of this year, measles alone increased 62 per cent over 1976.

In the underdeveloped countries, where 80 per cent of the world's children live, five million children die each year because basic immunization programs do not exist. Another 10 million survive but are permanently disabled.