Since there were few international opportunities for U.S. skaters, de Leeuw's mother decided she should try to compete for the Netherlands. She won her first national title in the 1970–71 season and was assigned to the 1971 European Championships in Zürich, where she placed 19th. To gain a berth to the 1972 Winter Olympics, de Leeuw was required to finish in the top ten at the 1972 European Championships. She managed to place ninth and made her Olympic debut, finishing 16th. She then made her first appearance at the World Championships.