I was so surprised when this happened to me! Baby was not due for another 4 1/2 weeks, and I'd suddenly found that when I stand up I suddenly leak a little 'urine'. Only it filled a sanitary towel in seconds, before stopping again.
I was convinced it was pregnancy related urinary incontinence, until that night at 3am I got up to empty my bladder and immediately afterwards had another 'gush'.
I googled how to tell if it's urine or amniotic fluid, and there were a few differences; amniotic fluid can be clear and odourless, but then again so can very diluted urine! The best tip seemed to be trying pelvic floor exercises to 'stop' the gush - allegedly if it stops then its urine, but if it doesn't then it's not.
The problem was that by the time I had begun pelvic floor exercises the gush stopped and I couldn't tell if it was of the pelvic floor exercises stopping urine, or whether it was because the amniotic leak stopped itself again naturally!
Within about 8 hours I developed a low period pain after each gush of water and then eventually the amount increased and became pink tinged. By the time I got to hospital I was 4cm dilated and within 2 1/2 hours I had got to 8cm dilated!
Waters it was then!!!!
I just thought it might help anyone else to know that waters don't necessarily leak all the way through beds, clothes and on restaurant floors like portrayed in the films 