From your question it sounds like you are not already in medical school (if you are you should really be talking to your dean!!)
so here is how it goes in the US, (it is very different in Europe)
after you graduate high school you have to get a Bachelor's degree (usually 4 years)
then you go to medical school for 4 more years
then residency depending on the field:
OB/GYN: 4 years
Family Medicine: 3 years
Internal Medicine: 3 years
Pediatrics: 3 years
Anesthesiology: 4 years (1 year internship + 3 years)
Psychiatry: 4 years
General Surgery: 5 years
-there are also some surgical fields which are separate like Orthopedic Surgery (5 years), Neurosurgery (6-7 years)

Lot of these fields have sub-specialties (fellowship) that you can do afterwards usually 1 or 2 years.

Good luck

Gynaecology or gynecology refers to the surgical specialty dealing with health of the female reproductive system. Gynaecology is typically considered a consultant specialty.

The gynecological problems encountered in children and adolescents are often both medically and psychologically complex and thus require a highly skilled and coherent approach. The adolescent, who is no longer a child but not quite an adult, poses a particular management problem to the traditional specialties.

Pediatric and Adolescent Gynecology includes all aspects of clinical and basic science research in pediatric and adolescent gynecology, as well as molecular biology research as applied to the field. The Journal draws in expertise from a variety of disciplines including pediatrics, obstetrics and gynecology, reproduction and gynecology, reproductive and pediatric endocrinology, genetics, and molecular biology.

In the field of adolescent gynecology more than anywhere else, the medical attitude is often striking by its extremes: from a seemingly indifferent 'wait-andsee' policy (true indifference or ignorance?) to an overzealous interventionism – and this at a developmental moment requiring great sensitivity and tact.

Pediatric adolescent gynecologists:

Importance of adolescent gynecology:

Adolescents:
For adolescents, the first gynecologic examination provides a golden opportunity to educate young patients about the breast and pelvic exam, to answer questions about development, and to provide medical reassurances and information about issues of health and sexuality. The Division of Pediatric and Adolescent Gynecology provides abstinence counseling, as well as contraceptive counseling and pregnancy prevention strategies. Adolescents especially may benefit from counseling about the risks of sexual activity and the prevention of sexually transmitted diseases.

Physician:
Division Director Dr Elizabeth Poynor, MD, PhD is considered a national expert in this field, and provides training in pediatric and adolescent gynecology for other physicians. She has received advanced training in the subspecialty practice of pediatric and adolescent gynecology.

You can visit: www.drelizabethpoynor.com