Stretch Marks by Marlene Katz According to the book Stretch Marks, From Their Clinical Aspects to Their Treatment, written by Dr. Nina Roos and Dr. Anny Cohen-Letessier, stretch marks are extremely common and develop before the age of 50. They affect more than 40 to 50 percent of the young population, mainly Caucasians, essentially female (60 to 80 percent women compared to 10 to 30 percent men.). They mainly develop during puberty, with a variable overall incidence depending on the series: from 25 to 35 percent up to 70 percent of girls and 40 percent of boys. Concerning pregnant women, according to the authors, 50 to 90 percent of primiparae will develop stretch marks as of the 6th month of pregnancy on the stomach, the breast, or hips. Copyright© PR Newswire United Business Media Want to read more? Subscribe to one of our monthly plans to continue reading this article.