The societal pressures on women to be attractive, successful, and thin are stronger than ever. The desirable woman portrayed in the media is much thinner than the average woman. Popular slogans such as "thin is in" and "you can never be too rich or too thin" have equated thinness with happiness. The result is that for the first time in history, being attractive means being thin.
Healthy weight women have an easier time getting pregnant than overweight or underweight women. Studies show that women whose body mass index (BMI) is below 20 or above 25 (especially above 30) have a harder time getting pregnant, so it's a good idea to try to get yourself into the 20 to 25 range before you start trying.
According to Dr. Fady Sharara, board-certified reproductive endocrinologist and Medical Director of the Virginia Center for Reproductive Medicine, being underweight can affect a woman’s fertility, due to reduced body fat that can affect ovulation. “Even moderate weight loss of 10-15% under the ideal body weight can result in an irregular menstrual cycle,” says Dr. Sharara. This contradicts the popular belief that only dramatic weight loss of 30% or more-commonly found in women with anorexia nervosa and bulimia-will lead to menstrual irregularities. Studies show that up to 73 percent of these underweight women who have been able to achieve 95 percent of their ideal body weight, have restored ovulation and pregnancy.