What is the official source for the following question:

Teenage girls in a relationship with an older boy are more likely to
have sex and to get pregnant.

Hello - and thank-you for your question.

I believe you are looking for research carried out by Dr. Jacqueline
Darroch and colleagues from the Alan Guttmacher Institute, published
in "Family Planning Perspectives",  Volume 31, No. 4, July/August
1999.  See:

http://www.guttmacher.org/pubs/journals/3116099.html

It includes this information:

"Among women younger than 18, the pregnancy rate among those with a
partner who was six or more years older was 3.7 times as high as the
rate among those whose partner was no more than two years older."

and:

"Pregnancy rates are clearly highest for the teenage women with the
oldest partners; such a situation is troubling to the public because
it raises the concern that the age difference may make it more
difficult for young women to resist pressure to have sex and to become
pregnant."

I hope this is helpful.  Please feel free to ask for clarification if
needed.

Regards - Leli


search notes:

Searching with 'US teenage pregnancy statistics' led here:

://www.google.co.uk/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=us+statistics+teenage+pregnancy&spell=1

Then a reference on this site led me to the Alan Guttmacher Institute:

http://www.plannedparenthood.org/Library/teen-pregnancy/teenpreg_fact.html

Thanks, this is more than what I was looking for.