The term "power" is often used when describing gender differences. "Power" is a broad concept that describes the ability or freedom of individuals to make decisions and behave as they choose (52, 53, 115, 187, 202). It also can describe a person's access to resources and ability to control them. When the term "power" is associated with gender, it usually refers to inequities between men and women.

Two types of power help to describe the inequities in male and female gender roles—"power to" and "power over." "Power to" describes the ability of individuals to control their own lives and to use resources for their own benefit. For instance, a man is more likely than a woman to have the power to go where he wants, find a good job, and earn money. "Power over" means that individuals can assert their wishes, even in the face of opposition, and force others to act in ways that they may not want to (115, 202). In many cultures, for example, men make reproductive decisions, such as how many children their wives will have, that can have consequences for women's health and well-being (72, 73, 106,157).

Differences in power between men and women are not absolute or universal. Some men, especially those who are poor, illiterate, unemployed, or homosexual, usually have little power and few resources (20, 25). Also, especially among younger men and women in some cultures, gender roles are changing toward more equality.

Women's gender roles do give them some power. Usually, however, it is much more limited in scope than men's (15, 89). Like a man's power, a woman's power is influenced by such factors as her culture, age, income, and education. Some studies have found that women's power increases as their status in the community improves (36, 164). In Nigeria, for example, Yoruba women who have many children, especially sons, have more say than their husbands about whether or not they will have more children. Among Yoruba women with few or no children, however, their husbands' fertility desires usually prevail (17).

Type of marriage also can affect a woman's power. If a woman can choose her husband, she usually has more influence within her marriage than if her family chooses her husband (89, 138, 140). A woman's power to make decisions sometimes increases with her level of education and also with her husband's level of education. It may also depend on her age. Generally, younger women who marry much older men have less power than women who marry someone closer in age (15, 65, 89).

Gender roles begin at birth and span a lifetime. At very young ages boys and girls learn from their families and peers how they are expected to act around people of the same sex and of the opposite sex (39, 283). Almost universally, adolescent males experience more sexual freedom than adolescent females. Potentially harmful sexual attitudes and behavior that can develop during youth are often difficult to change during adulthood.

Because gender lies at the heart of social organization and the distribution of power, calls for changes in gender roles, and hence behavior, often touch emotional and political nerves. Some people see such change as threatening, while others see it as part of the global trend toward equality and justice (262). However sensitive the topic, taking a fresh look at how gender affects reproductive behavior is a necessary step toward improving reproductive health for all (53, 104, 110, 187, 262).