Despite early inroads of school-based sex education, most of the information on sexual matters in the mid-20th century was obtained informally from friends and the media, and much of this information was deficient or of dubious value, especially during the period following puberty, when curiosity about sexual matters was the most acute. This deficiency was heightened by the increasing incidence of teenage pregnancies, particularly in Western countries after the 1960s. As part of each country's efforts to reduce such pregnancies, programs of sex education were introduced, initially over strong opposition from parent and religious groups.