Rachel Jones, a senior researcher at the Guttmacher Institute for reproductive health, told reporters that the inventor of the original pill incorporated a week of bleeding into the regimen, not only to gain support from the Catholic Church, but because many women found it "reassuring."
In 1986, Beverly Strassmann, associate professor of anthropology at the Institute for Social Research at University of Michigan, began a two-year study of menstruating women in West Africa. Keeping a check list of village women's cycles, she noted that those women spent most of their lives not menstruating.
Women in their fertile years were either pregnant, lactating or wet nursing. Menstruation occured primarily in younger teens and women approaching menopause, she said.
According to Strassmann, women do not need to menstruate to stay healthy — rather, it is exposure to hormones during the 28-day cycle that leaves women vulnerable to increased cancer risks.
"The reproductive cancer connection is real," she said, citing studies that have shown celibate nuns have the highest prevalence of breast cancer.
"We shouldn't worry that it's unnatural," said Strassman. "Menstruating every month is not the natural course of events. Some women have been slow to accept that and have been proselytizing that they must have a menstrual cycle every month."
But it is menstruation that has historically set women apart from men. A quirky Web site called the Museum of Menstruation chronicles tales of both humor and shame. It quotes the 19th century Canadian-American physician Sir William Osler as referring to the flow as "the tears of a disappointed uterus."
Today, both men and women have different attitudes toward menstruation. Indie rock vocalist Ani DiFranco sings with 21st century attitude about her monthly cycle: "I woke up one morning covered in blood, like a war — like a warning that I live in a breakable takeable body."
Whether Lybrel is a sign that women have "come a long way, baby" or embraced a "Brave New World," is irrelevant, say sociologists.
The new pill represents new options for women in defining their own identities, said Stuart Michaels, assistant director of the Center for Gender Studies at the University of Chicago. And the term "natural" is defined by cultural values, not biology, he said.
"What is natural is not a simple and absolute determination," said Michaels. "One woman might take the pill ... because it has certain benefits in preventing pregnancy, and she may or may not have any doubts about her femininity."
"Someone else might choose to do this because she doesn't want to menstruate because it makes her feel unfeminine," he said. "It's all about how people experience their own body and think about what it means to be a man or woman."