Most Teens Have No Sex Education Before Sex By John Johnson, Newser Staff Posted Apr 8, 2014 3:45 PM CDT 76 comments Comments (Shutterstock) (Newser) – The number of teens aged 15 to 17 giving birth continues to drop, but that group still delivers 1,700 babies a week in the US, reports NBC News. That's way too many, says the CDC, which thinks part of the reason can be found in another newly released stat: Among teen girls with sexual experience, 83% say they had no formal sexual education before their first encounter, reports the LA Times. That percentage “represents a missed opportunity to introduce medically accurate information,” says CDC researchers in a new report. Overall, the study found that 14.6% of 15-year-olds, 28.5% of 16-year-olds, and 38.6% of 17-year-olds have had sex at least once, and only 15% of those used a form of contraception deemed at least moderately effective, such as the pill, a vaginal ring, an IUD, or a hormonal implant. Most (62%) used less effective forms, including condoms and sponges, and 23% used nothing at all. “We are missing opportunities to deliver messages before teens begin to have sex,” says a CDC official.