Unsafe sex is the second most prevalent health risk worldwide, ranking just behind poor nutrition/being underweight, according to a World Health Organization report released Wednesday, Agence France-Presse reports. The report, titled "Reducing Risks, Promoting Healthy Life," lists the world's top 10 health risks. According to the report, unsafe sex is far more prevalent in developing nations than in developed countries and can lead to a number of sexually transmitted diseases, primarily AIDS. The report lists AIDS as the world's fourth leading cause of death, with 2.9 million deaths per year directly linked to unprotected sex. The report encourages cost-effective measures to battle the top health problems, including HIV-prevention education and counseling to promote condom use.