You can find this information on PubMed but this is a nice summary from UpToDate (only brief highlights are posted below, check the source link for full text):

Sexually transmitted infections

25% of urban adolescent females (14-17 years of age) were diagnosed with a sexually transmitted infection (STI) within one year of first intercourse.

Attention deficit hyperactivity disorder (ADHD)

ECG screening should not be required before initiating stimulant therapy for patients with ADHD.

Autism prevalence

The prevalence of autism spectrum disorders (ASD) among eight-year-old children in the United States increased from 1 in 150 children in 2000 to 2002 to approximately 1 in 111 in 2006. No clear reason for increase has been found.

The choking game

5.7% of eighth-graders had participated in the self-strangulation activity known as "the choking game". Recognize signs of these activities: bruising or red marks on the neck; wearing high-necked shirts, even in warm weather; bloodshot eyes or pinpoint bruising around the eyes; petechiae on the face, especially the eyelids or conjunctiva.

HPV vaccine

The US Food and Drug Administration (FDA) approved the use of quadrivalent human papillomavirus vaccine in males aged 9 through 26 years to reduce their likelihood of acquiring genital warts.

13-valent PCV

The FDA approved a 13-valentpneumococcal conjugate vaccine (PCV13). PCV13 adds serotypes 1, 3, 5, 6A, 7F, and 19A to those contained in the PCV7, the 7-valent vaccine (4, 6B, 9V, 14, 18C, 19F, and 23F). The six additional serotypes accounted for 63% of invasive pneumococcal disease among children younger than five years of age.

References:
What's new in pediatrics. UpToDate.