; (B) an area in an urban or rural area (which need not conform to the geographic boundaries of a political subdivision and which is a rational area for the delivery of health services) which the Secretary determines has a shortage of hospital or labor and delivery units, hospital birth center units, or freestanding birth centers or an area that lost a significant number of these units during the 10-year period beginning with 2004; or (C) a population group which the Secretary determines has such a shortage of providers or facilities. . 519. Expansion of CDC prevention research centers program to include centers on optimal maternity outcomes (a) In general Not later than one year after the date of the enactment of this Act, the Secretary of Health and Human Services, shall support the establishment of additional Prevention Research Centers under the Prevention Research Center Program administered by the Centers for Disease Control and Prevention. Such additional centers shall each be known as a Center for Excellence on Optimal Maternity Outcomes. (b) Research Each Center for Excellence on Optimal Maternity Outcomes shall— (1) conduct at least one focused program of research to improve maternity outcomes, including the reduction of cesarean birth rates, elective inductions, prematurity rates, and low birth weight rates within an underserved population that has a disproportionately large burden of suboptimal maternity outcomes, including maternal mortality and morbidity, infant mortality, prematurity, or low birth weight; (2) work with partners on special interest projects, as specified by the Centers for Disease Control and Prevention and other relevant agencies within the Department of Health and Human Services, and on projects funded by other sources; and (3) involve a minimum of two distinct birth setting models, such as a hospital labor and delivery model and freestanding birth center model