SACRAMENTO, Calif. -- Shirley Berger holds a photo of herself taken at Venice Beach, Calif., in 1960. She's about 20 in the picture and looks like Elizabeth Taylor: the same thick eyebrows and upturned nose. She's on her stomach, holding a cigarette. A layer of her dark curly hair covers her head.

"My hair was so thick, you couldn't see through it at all," Berger said. "I had a ton of hair."

At 58, 10 years after she hit menopause, her hair started to thin and fall out. She bought a wig, but she hated how it felt.

She goes to the hairdresser once a week now for help hiding the thin spots. At restaurants, she maneuvers herself out of the way when waiters come to the table so they can't see the top of her head. And she sleeps on satin pillowcases to avoid snagging her hair.

"I'm not sure I understand why men can get away with aging," said Berger, who is now 70.

Sitting in her Carmichael, Calif., home, she splays old photos across her kitchen table. A few feature the sky-high 'do she wore in 1976.

"It's scary because all of a sudden you knew, just looking in the mirror every day, you knew you were aging. ... I would give anything if I had not lost my hair," she said.

Aside from menopause, the American Academy of Dermatology reports that 30 million women in the United States are losing their hair due to genetic factors. Thyroid disease, medication side effects and diet also can cause it.

It's estimated that one in four women experiences thinning hair.

"With some, it has to do with dramatic changes in their life: surgery, delivering a child ... having a very severe illness," said Pamela Prescott, an endocrinologist at the University of California-Davis Medical Center. "Sometimes, it's what we do to our hair, the styling, dyeing, straightening."

Stress, Prescott said, can have a major effect on hair growth. And for some, losing their hair gives them more reason to stress than the actual medical cause.

"It was very traumatic," said Kristy DeVaney, who lost all her hair after having a negative reaction to the common antibiotic minocycline. "It was very hard to deal with for a very long time. ... I kept thinking, 'What do people think of me? What do I think of myself? I'm an ugly bald person.' It's probably the worst thing I've ever been through."

Maxine Craig, an associate professor in the Women and Gender Studies program at UC Davis, has researched just how much hair means to women.

It means a whole lot.

"Hair is seen as a marker of gender identity," Craig said. In most Western cultures, short hair or no hair represents masculinity, and long hair represents femininity.

"These are social codes that we all learn and learn deeply," Craig said. "When a woman loses her hair, she may feel that she is losing something that identifies her as a woman."

Girls who cut their hair short and men who grow their hair out are considered rebels -- people who want to resist the social code and be defiant.

"Women who do not attempt to confirm to beauty norms are seen as somehow problematic," Craig said. "Girls start hearing at a very young age that their looks are important ... and women are constantly getting evaluated on the basis of their appearance."

There is, perhaps, no better spokeswoman for the issue of baldness and beauty than Miss Delaware 2010 -- and a Top 10 at this year's Miss America pageant -- Kayla Martell.

Martell is completely bald, the result of alopecia areata, an autoimmune disease that caused her hair to start falling out when she was 10.

"I remember thinking, 'I probably will never be Miss Delaware now,"' said Martell, who had grown up attending the state pageant every year with her mother.

She entered the pageant, and three times she strutted across the Miss Delaware stage sporting what she described as "peach fuzz" on her head. Eventually, a judge pulled her aside and told her that if she wanted to win the crown, she needed to wear a wig.

"I was so offended and appalled, I couldn't believe what I was hearing," she said.

But after talking about it and seeing people at alopecia conferences wearing wigs, she changed her mind. Winning the pageant would give her a higher public platform from which to talk about women's baldness.

"All I asked was for the judges to support me if I could go on TV and do interviews without my hair on," she said. They agreed, and she competed with the wig. To her relief, she lost.

"Obviously I didn't enjoy not winning," she said. "But I feared that if I won the very first time with a wig, so many people would say, 'She only won now because she wore the wig."'

It took one more try before Martell -- again with her wig -- was crowned Miss Delaware.