A woman and her gynaecologist

A middle-aged woman visits her gynaecologist.
“I’ve been have a few problems,” she says, “On Monday I went to the toilet and I heard a plink. When I looked down, the water was full of pennies.” On Tuesday a similar thing happened but the coins were 5 pence pieces. This morning the same thing happened but the coins were 10 pence pieces. What’s wrong with Doctor?”
“Don’t worry,” the gynaecologist replies comfortingly, “You’re simply going through the change.”