Female body shape or female figure is the cumulative product of a woman's skeletal structure and the quantity and distribution of muscle and fat on the body. There is a wide range of normality of female body shapes. Female figures are typically narrower at the waist than at the bust and hips. The bust, waist, and hips are called inflection points, and the ratios of their circumferences are used to define basic body shapes. Reflecting the wide range of individual beliefs on what is best for physical health and what is preferred aesthetically, as well as disagreements on the social standing and purported "purpose" of women in society, there is no universally acknowledged ideal female body shape. Cultural ideals, however, have developed and continue to exert influence over how a woman relates to her own body, as well as how others in her society may perceive and treat her. Physiology Impact of estrogens Estrogens, which are primary female sex hormones, have a significant impact on a female's body shape. They are produced in both men and women, but their levels are significantly higher in women, especially in those of reproductive age. Besides other functions, estrogens promote the development of female secondary sexual characteristics, such as breasts and hips. As a result of estrogens, during puberty, girls develop breasts and their hips widen. Working against estrogen, the presence of testosterone in a pubescent female inhibits breast development and promotes muscle and facial hair development. Estrogen levels also rise significantly during pregnancy. A number of other changes typically occur during pregnancy, including enlargement and increased firmness of the breasts, mainly due to hypertrophy of the mammary gland in response to the hormone prolactin. The size of the nipples may increase noticeably. These changes may continue during breastfeeding. Breasts generally revert to approximately their previous size after pregnancy, although there may be some increased sagging. Breasts can decrease in size at menopause if estrogen levels decline. Fat distribution Estrogens can also affect the female body shape in a number of other ways, including increasing fat stores, accelerating metabolism, reducing muscle mass, and increasing bone formation. Estrogens cause higher levels of fat to be stored in a female body than in a male body. They also affect body fat distribution, causing fat to be stored in the buttocks, thighs, and hips in women, but generally not around their waists, which will remain about the