THERE WILL BE stories today about the very first infant born in this and that jurisdiction in the New Year, the 12:01 a.m. generation. Those unhappy looking baby human creatures, howling their lungs out, are part of something more interesting than you -- and surely they at this moment -- suppose. One of the statistics that tells you most about current attitudes in a society -- and about its future -- is the birth rate. Birth rates reached record lows in the depressed 1930s and rose to unanticipatedly high levels in the bouyant economic growth years after World War II. The record low birth rates of the last 15 years have been accompanied by the entry of women into the work force in large and unanticipated numbers and by striking changes in cultural and moral attitudes.

Now there are signs -- lower divorce rates, for example -- that some of these cultural attitudes are changing. But those who think we are headed back into the 1950s should ponder the latest news on birth rates. For the year ending in June 1984, the number of children born per 1,000 women of childbearing age is lower than ever. The birth dearth continues.

The figures tell some other interesting stories, relevant to public policy. First, poorer and less educated women are much more likely than their upscale counterparts to have children. This means that increasingly we are becoming -- to exaggerate a bit -- a nation of rich adults and poor children. The need for government programs that give poor children a fair chance for good health and a good education will continue.

The need for day care services of some kind evidently will increase too. Nearly half -- 47 percent -- of mothers of children under one year were in the labor force in 1984, compared with 38 percent in 1980 and 31 percent in 1976. Not all of these women hold or seek full-time jobs. But there is obviously a weakening of the traditional belief that mothers of young children must remain in the home. Both those who hail and those who deplore this trend should be concerned about the care these young children receive and should ask whether government can do things to make it better.

Not all the trends point in exactly the same direction. The birth rate of women in their early 30s is up, indicating that some products of the baby boom have been only postponing having children rather than deciding not to have them altogether. But the rise is small and does not counterbalance the general decline. Black and Hispanic women continue to have more children than whites. But the difference between blacks and whites is not large, and the high birth rate among Hispanics is typical of the historical experience with groups with large percentages of immigrants.

A dozen years ago, many observers feared there would be too many Americans; now many fear there will be too few. The long-run implications for the military manpower pool and the balance between taxpayers and Social Security recipients are genuinely unsettling. There is, however, this comfort: the line on the birth-rate graph has always shifted, usually when people expected it least and for reasons that usually became apparent only long afterward. In demographics, as in sports, there is always a next year.