In a paper looking at female genital cosmetic surgery, it says women and girls should realise that female genitalia come in all shapes and sizes.
They should also be told of the risks of this type of surgery.
Labiaplasties on the NHS have risen fivefold in the past 10 years.
Labiaplasty is the most common type of female genital cosmetic surgery, in which the size of the labia minora is reduced.
It can be a treatment for women who have concerns with hygiene, difficulties during sexual intercourse or discomfort when exercising, but some women and girls want surgery because of concerns about the way their genitalia look.
In extreme cases this can be linked to body dysmorphic disorder, which causes significant anxieties about body image.
Statistics show that more than 2,000 labiaplasty operations were performed in 2010 on the NHS.
Many more are carried out by private clinics but there are no figures available on these procedures, although the RCOG says "the practice of labiaplasty is now widespread".
Dame Suzi Leather, chair of the RCOG's ethics committee, said there was concern over the recent figures.
"Some women are requesting it solely for cosmetic reasons and these decisions are not always being made on an informed understanding of the normal variations that exist, but influenced by images from popular culture and the pornography industry.
"We need to inform women that everyone is unique and that variation in appearance is normal in the vast majority of cases," she said.
The RCOG paper recommends that women should be offered counselling and psychological treatment for problems such as "body image distress".
The paper says: "Education, support and advice should be at the heart of clinical practice, with a sympathetic appreciation of female body insecurities."
Official stats show that the labiaplasty procedure is not restricted to adults. In the past five years, 266 of these procedures have been carried out on girls under 14.
While the reasons for the procedures are unknown, they are likely to have been performed for medical reasons or to correct congenital abnormalities.
In another paper, published by the British Society for Paediatric and Adolescent Gynaecology (BritSPAG), clinicians are advised to inform girls under 18 that labiaplasty surgery before puberty is complete can lead to long-term problems.
Although no research has been carried out on these long-term risks, it is thought that damage to sexual function and sensitivity can occur after labiaplasty. Bleeding and wound infection can also occur in the short term.
The paper also recommends that girls showing signs of psychological problems should be referred to a paediatric clinical psychologist.
Consultant plastic surgeon Paul Banwell, from the British Association of Aesthetic Plastic Surgeons, welcomed the recommendations published in both papers and said patients should always be given full, accurate information and be properly counselled before surgery.
But he said clinicians should also be sensitive to potential problems.
"An asymmetrical labia can lead to functional problems as well as aesthetic problems. Over 50% of my patients see me due to functional reasons. Only a small proportion are there for purely aesthetic reasons."
He also said he had seen the number of patients requesting labiaplasty increase dramatically in the past few years.
Tim Goodacre, head of professional standards at the British Association of Plastic, Reconstructive and Aesthetic Surgeons and a consultant plastic surgeon, said he supported the recommendations as a means of improving patient care.
"We would like to see tougher central regulation of the cosmetic surgery industry to help clamp down on anyone performing these operations unnecessarily, and without due consideration for patient care."
But he said he found attempts to increase profits by encouraging more female genital procedures "abhorrent".
He added: "We urge stringent and robust restrictions on advertising such operations with a firm objective to limit any material other than that with information only. All advertising that could in any way be seen as persuasive should be banned."
"Designer vagina" surgery should not be carried out on the NHS or on girls under the age of 18, the Royal College of Obstetricians and Gynaecologists has said.