This means that women are not reproducing fast enough to replace our population numbers. The “replacement level fertility,” as it is known, is 2,100 births per 1,000 women over their reproductive lifetime, the CDC said. In 2017 only South Dakota, with 2,227.5, and Utah, with 2,120.5, had a total fertility rate (TFR) above replacement level, the CDC’s National Center for Health Statistics said in its National Vital Statistics Report released on Thursday. The District of Columbia had the lowest rate, with 1,421.