Final answer:
The likely reason for lower teenage pregnancy rates in European nations compared to the U.S. is attributed to the comprehensive and mandatory sex-education curriculum in Europe, emphasizing safer sexual practices and contraception.
Step-by-step explanation:
One reason that the teenage pregnancy rate in most European nations is less than half of that in the United States may be because of the European sex-education curriculum. European nations such as Sweden, Switzerland, and the Netherlands are known for their comprehensive and mandatory sex education programs that begin early in the schooling years. These programs often place a high emphasis on safer sexual practices and the use of contraception, contributing to lower rates of teenage pregnancy and sexually transmitted infections.
In contrast, the United States does not mandate sex education in all public school curricula, and there is controversy over what type of sex education should be taught. Despite studies showing that a majority of U.S. adults support education about safer sexual practices over abstinence-only approaches, there is no uniform approach across the country. This lack of comprehensive sex education can lead to higher rates of unintended pregnancies and STIs among teenagers.