Most adolescents are unprepared the first time intercourse occurs.
Definition of Terms Pregnancy Rate number of pregnancies population, usually multiplied by 1,000. Calculating Rates Proportion of Pregnancies Ending in Birth, Abortion, or Miscarriage number of births, abortions, or miscarriages number of pregnancies, multiplied by 100. Definition of Terms Birth Rate number of births population, usually multiplied by 1,000. Proportion of Teen Births to Unmarried Teens number of births to unmarried teens total number of births in the same age group, multiplied by 100.