An obscure but influential program that gave detailed public health information to about half of the world’s nations will fold as a result of the Trump administration’s freeze on foreign aid. With funding from the United States Agency for International Development, the Demographic and Health Surveys were the only sources of information in many countries about maternal and child health and mortality, nutrition, reproductive health and H.I.V. infections, among many other health indicators. The surveys collected data in 90 low- and middle-income nations, which then used the information to set health benchmarks at the local, national and global levels, including the 2030 Sustainable Development Goals adopted by member countries of the United Nations. On Tuesday, the program’s administrators learned that it was being “terminated for the convenience of the U.S. Government,” effective immediately, according to an email viewed by The New York Times. They were ordered to “stop all work, terminate subcontracts and place no further orders.”