The pill divided mothers and daughters in its early days. Married women had clamored for it as soon as it went on the market — within two years of its approval, more than a million women were taking it. But that didn't mean they wanted their unmarried daughters to have it.

"I talk to my daughter about the pill a lot more than I talked to my mother about the pill," said Jean Elson, 61, a sociologist and expert on women's health at the University of New Hampshire. Elson secretly started taking the pill in college in the late 1960s before she was married. Her mother wouldn't have approved.

"The only conversations about sex I remember with my mother were 'not to.' I remember warnings about tongue kissing. She didn't do that until she was engaged," Elson said.

Many parents now discuss birth control with their unmarried daughters and sons. They also may discuss condoms to prevent disease, including AIDS. The greatest fear associated with unprotected sex for young people is no longer pregnancy, it's serious sexually transmitted disease.

Another change is advertising. Women now in their 20s have seen ads for the pill nearly their entire lives. The first magazine ads for the pill ran in 1992. Now TV ads show smiling women liberated by the ability to limit or even eliminate their menstrual periods.

"The message is your period shouldn't get in the way. It's an appealing message," said Sarah Forbes, 28, curator of the Museum of Sex in New York. Her generation takes the pill for many reasons and they take it for granted.

"We're so used to it being so freely available," Forbes said. "It's almost impossible to think of a world where we didn't have access to it."

The pill is so ubiquitous that young women may have trouble learning about other options. Tone said one doctor said he didn't remember how to fit a diaphragm, a flexible shield that covers the cervix. The pill is so highly marketed that other methods, like implants and IUDs, aren't clearly understood by young women.

"We've got choices, but the information about them isn't always well balanced," said Judy Norsigian, 62, executive director of Our Bodies Ourselves, the nonprofit organization that publishes the long-standing women's health guide of the same name.

Female doctors use IUDs twice as frequently as the general population of women and many recommend it to their patients.

"The future of birth control is not pills at all," said Dr. Lisa Perriera, 34, of Case Western Reserve School of Medicine in Cleveland.

"The best birth control is easy to use, highly effective at preventing pregnancy and has few side effects," Perriera said. "The methods that fit those criteria best are IUDs and implants. I think that's where birth control is going."

Others hold out hope for a breakthrough in male-centered birth control. An oral drug called miglustat worked in mice, but not in men. Researchers are recruiting men for studies of a hormonal gel to suppress sperm production.

"The question is will a single company decide to take this to market, to get FDA clearance, a very expensive undertaking, when it's hard to predict how commercially viable a male pill would be," Tone said. As much as women would like men to be equal partners in preventing pregnancy, "women at the same time feel a little bit nervous entrusting men to take a pill or be on a patch."

After all these years, a male equivalent to the birth control pill is still five to seven years away.