This happened to me as well at midnight, it turns out my water had broken. It was warm, a tad thicker than urine and didn't have a strong smell at all. If your Dr doesn't call, then call the hospital maternity floor and ask. If it is a slight greenish in color than it is amniotic fluid with meconium... which means baby has pooped in the amniotic fluid and is likely in fetal distress... so you need to go to the Dr now. Lie down on your side, the baby's head won't be blocking the opening and if it is still leaking that is likely amniotic fluid. Here is a good test to tell what that fluid is:
"The easiest thing to do to tell if it is your water or urine is to put on clean, dry underwear and a pad or panty liner. Then you'll want to lay down for about a half of an hour. If the fluid is amniotic fluid, it will pool or gather in the vagina while you lay down.
During this half an hour, spend time gathering your thoughts. Are you packed and ready for the trip to the hospital? Do you need to call anyone like your husband or doula? Try to do a fetal kick count or make note of your baby's movements as well. You can also use the time to take a quick nap.
At the end of the time, simply get up and go back to the bathroom. Here is where we checked to see if the pad is wet or dry. A dry pad means that your water is most likely not broken. What you experienced could have been an increase in mucus discharge, a small leak from your bladder or other common late pregnancy nuisances. If the pad is wet, you still might not have broken your bag of water. Look at the fluid. What color is it? Urine can many colors, but it is usually colored. Amniotic fluid is usually clear to pale straw colored (lighter than urine).
Smell the fluid. Does it smell like urine? If it smells like urine, it probably is urine. Bladder control issues are not uncommon in pregnancy. If it smells like bleach, it is more likely to be amniotic fluid. If you are still unsure about whether it was your amniotic sac breaking or urine leaking, call your doctor or midwife. They may advise you of other simple ways to test if it is amniotic fluid. They may also ask that you come into their office or the hospital to perform a small test on the fluid.
If you are asked to go in, bring everything you'd need to give birth with you in case they tell you to stay.Your doctor or midwife will use one of two common tests to see if the fluid leaking is your water or not. One simply involves a vaginal exam. During the vaginal exam, the doctor, midwife or nurse will introduce a small piece of paper, called litmus paper. This paper reacts by changing color when it is exposed to amniotic fluid. If the paper doesn't react, your water is not broken.
The other test is to take a small sample of fluid and look at it under a microscope. When amniotic fluid is dry the pattern it makes on the microscope slide looks like a fern plant and is therefore called ferning. So if they see ferning, your water has broken.
If your water has not broken you will be sent home to await the start of labor. If your water has broken, what happens next is dependent upon the protocols of your doctor or midwife. Good luck!"