There are rounding errors. That is, the denominator which was used to develop rates were extrapolated numbers. The number of births in the denominator were actual births. There were one or two counties where the number of births exceeded the number of women of child-bearing age and that anomaly occurred directly because of the imperfect extrapolation methods. This was particularly an issue in the data presented for minorities and for African Americans at the county level.
Statisticians frequently report birth rates.
These are the total number of births calculated as a proportion of the total number of people in an area. Birth rates are useful where the issue is overall population change or predicting, for example, the need for school classrooms. Fertility rates are useful in assessing the reproductive rate of child bearing women and may be more useful in determining need for pre-natal services, family planning and so forth. A birth rate may be high simply because there are a large number of women of child bearing age in the population, not that those women are having lots of children. A high fertility rate reflects a high rate of live reproduction among women of reproductive age.