Hanna Klaus is a Medical Mission Sister who served 7 years in Pakistan as an obstetrician gynecologist. On returning to the US she taught in the gynecology departments of Washington and St. Louis University Medical schools, St. Louis Missouri , then at the George Washington University in Washington D.C. She began to teach and research the Billings Ovulation Method in 1973 and cofounded the Teen STAR program in 1980. Currently the International Teen STAR Association has programs in 30 countries.