Nothing kicks the little girl out of you like the moment you see that first brown splotch on your undies.

One fine Saturday afternoon, you’re an innocent 11-year-old jumping up and down on the bed like the other kids and the next thing you know, you go the bathroom and find a quarter-sized bloodstain on your panties.

“I stared at it a long time, wondering how I could have hurt myself,” Donna, now in her forties, remembers. “When I figured out what it was, I sent my cousins home and went to bed. It was four in the afternoon, but I felt like I needed to lie down. My mother and sister laughed uproariously when they found me in bed, lying down because I was ‘sick.’” Donna had been given a booklet so she knew what was happening, but her overriding thought was “Oh no! There’s no going back now. This is it.”

“Our baby’s a woman now,” Lori remembers her mother telling her father. “I was so embarrassed — I didn’t want my father to know about my body.”

Nine-year-old Natalie burst into tears when her 12-year-old sister Christina told her that getting her period meant she could have a baby. “I misunderstood and thought she meant I was going to have a baby,” recalls Natalie, now a 34-year-old English teacher. “I felt much too young to have a baby.”

When Christina told another friend of hers one day that she was going to start bleeding through the same place she peed, her friend didn’t believe her. “She turned white, went outside, and threw up,” recalls Christina, now 40. “Apparently I forgot to tell her that it only lasts a few days at a time. She thought she was going to bleed for the rest of her life.”

And this was progress compared to what Christina’s own mother went through as a young girl. Her mother grew up in the 1940s in a poor family and had to wear hand-me-down overalls that were too small. The straps cut into her so sharply that her shoulders bled. When she told her mother she thought she had got her period, she was hauled off to the doctor to have things explained, a common practice at the time. The doctor checked her out and told her that she did not, in fact, have her period. Christina’s mom couldn’t figure out why he was looking “down there” and pointed to her shoulders: “No it’s here,” she whispered. Ignorance may be bliss, but I mean really, now.

Much of the secrecy and embarrassment surrounding our periods comes from the fact that menstruation isn’t just about bleeding; it’s the sign that a girl is growing up and becoming, gulp, a sexual being. Twenty-nine-year-old Krissandra thought she was dying when she first got her period as a teenager. In a way, part of her was.

“I think I realized that in a sense I was losing something: innocence, naïveté. It separated me from the girls who didn’t have their periods, and my male friends suddenly saw me differently.”

We don’t make nearly the same fuss when a boy has his first wet dream. Mom or Dad don’t waltz out with his stained sheets and announce, “Look, honey, our boy is a man now!”

But while Mom and Dad may proudly announce that their baby is a woman now, it quickly becomes clear that that’s about as much as anybody wants to hear about it.

“Aunt Flo is visiting,” we whisper in mixed company when someone asks why so-and-so is doubled over with cramps in the corner.

Tricia Warden writes about how getting her period made her feel like a secret spy in an essay in The Bust Guide to the New Girl World Order. “My mother told me when I got my period that I was to tell no one except her,” writes Warden. “I was forbidden to bring up the subject if men or boys were present because I was told it was an extremely private thing. To give it that certain neurotic paranoid afraid-of-your-own-sexuality flair she gave it a code name. I felt like an agent of espionage. The code name was Rosy. In this way I could communicate with my mother if others, especially males, were present.”

The message is clear: We’re happy to acknowledge you are now a sexual being, but please keep it under wraps and spare us the details. It’s a message not lost on the sanitary products (or, to use the even more cryptic term, the “feminine hygiene”) industry. It has built a more than $2-billion-a-year business on the premise that we can wear white jeans and go horseback riding without anyone ever knowing we’re bleeding.