Weight reduction, fertility and contraception

IPPF Med Bull. 1983 Oct;17(5):2-4.

Abstract

PIP: The significance of weight and body composition with regard to the fertile menstrual cycle has excited much interest. There is global imbalance of resources and problems of widespread chronic malnutrition in many 3rd world countries. This emphasizes the great importance of the possible effects of diet, body weight, and body composition on fecundity (ability to reproduce), fertility (reproductive performance), and pregnancy outcome. Frisch and Revelle suggested that a critical body weight is required for a girl to progress through puberty, menstruate, and finally develop ovulatory cycles. They postulated a direct relationship between weight and menarche and suggested that before menarche will occur at least 17% of the body weight needs to be made up of fat. The Frisch hypothesis is not universally accepted, and it seems highly unlikely that a single age unrelated body weight is always the trigger for menarche. Many of the data used in Frische's original studies were derived rather than directly observed. It seems likely that both body weight and composition are important and that the peripheral conversion of androgens to estrogens in fat plays a role in pubertal development, but the actual signal whcih triggers the hypothalamic events leading eventually through puberty to menstruation and ovulation remains unkown. Acute malnutrition, as seen during famine, is assoicated with a dramatic decrease in fertility. It is usually secondary to amenorrhea and annovulation. In developing countries weight related amenorrhea and delayed menarche are largely the result of nutritonal deprivation and the demands of lactation on women of boderline body weight, but a different pattern is seen in Western countries. The outstanding example of weight reduction resulting in infertility is seen in patients with anorexia nervosa. These women have extreme self imposed weight loss, a distorted perception of their body image, and disturbance in their attitude towards their feelings of hunger and satiety. Self imposed weight loss is the most common single cause of secondary amenorrhea seen in the Western world. While diagnosis of the gross anoretic is perhaps rarely missed, the more subtle degrees of weight loss and their effect on the menstrual cycle are often overlooked. Simple weight loss of more than 30% of body fat will cause menstrual dysfunction and ultimately amenorrhea. There is no clearly defined threshold between infertility and normal reproductive health, and there will always be women who become pregnant despite suboptimal weight. Patients with simple weight loss may be sufficiently motivated to restore their weight to normal levels, with resultant spontaneous resumption of ovulation.

MeSH terms

  • Amenorrhea*
  • Biology
  • Body Weight*
  • Demography
  • Disease
  • Fertility*
  • Infertility*
  • Menarche*
  • Menstruation
  • Menstruation Disturbances*
  • Nutrition Disorders*
  • Ovulation*
  • Physiology
  • Population
  • Population Dynamics
  • Pregnancy*
  • Reproduction
  • Therapeutics