Keep the dialogue open with your daughter. Don't freak out in front of her or she will feel like she can't come to you. My daughter has thrown SEVERAL "time to freak out" things at me over the last couple of years, and so far, we still have a great relationship and can talk. I HOPE it's because I do my very best to stay outwardly calm no matter what she says and have a "friend" conversation with her when she brings up uncomfortable subjects.
Ask your daughter what sex is and let her tell you. It may be that she has heard the word but DOESN"T know all the grown up details. Fill in the blanks if she needs you too, but keep it G rated.
Last year, my SIL was pregnant. My daughter, then 8, had been asking many questions over several months and her questions kept escalating, so I knew she wasn't getting the answers she wanted. She asked me one night "what kind of food do you eat to get a baby in your belly?" So I said "When Mommy's and Daddy's get married and want to have a baby, they have sex. And sex is what makes a baby." (We haven't had a "sex" talk, but just the WORD is still a big deal to her).
She waited a few seconds and said "Is that what Aunt --- and Uncle --- did?" and I said yes. She ended with "Oh okay" and that was the end of it.
I also find that advice from my mother on any "taboo" subjects don't help much. When I was growing up, we were silently led to believe that it was all dirty. And you definitely didn't talk about touching any parts of your body. My mother still tends to highly over-react but I know that's just the way she was brought up.
Follow YOUR own motherly instincts any time these subjects come up. And pray for me that I can keep the lines of communication OPEN with my daughter through the coming years. That's my biggest fear, losing the freedom that she feels that she can bring any subject to my attention.
GOOD LUCK!!!
C.