No one tells you this ahead of time, but by the end of it, you will either be changing your underpants many times a day, or making good friends with a box of pantiliners. Even just normal vaginal fluid often greatly increases throughout pregnancy, not to mention sometimes leaking a bit of urine while coughing, laughing or perhaps even sleeping.
But what if you wake up soaked? How do you know what it was and what to do about it? The first thing you need to do is get yourself to a bathroom and observe a few things. Do you need to pee? Can you pee? If you can, then you should! Is there any red or pink on the toilet paper when you wipe? If yes, this is a great sign. Next, go back to the wet spot (either in your bed or in your underpants) and observe the color of the fluid in question? Urine is light yellow and has an odor everyone is familiar with, especially when you get up really close for a good whiff. Amniotic fluid is clear* and has either no odor*, or can occasionally smell a touch like semen. If you've had sex in the last 24 hours, this is a consideration, but if you haven't or there is a LOT of liquid, this is likely not the culprit.
The next test is to put on clean underpants and wait awhile. If your water has broken, more often than not, it will continue to leak. If your new underwear is wet within the hour, its a pretty safe bet that you are ruptured. (That's doctor-speak for YOUR WATER BROKE!!!!!!)
However, if you still aren't sure, put on a maxi pad (the kind you'd use for a period) and try to go back to sleep. The next time you wake up to pee -- it won't be too long, you're 9 months pregnant, remember? -- check to see how wet the pad is.
It is also possible for your bag of waters to spring a leak and leak slowly for a few days. This kind of leak can sometimes lead to labor and sometimes it will repair itself. True story.
Another little-known fact is that your water can break TWICE! Each amniotic sac is actually comprised of an amnion and a chorion, like two balloons, one inside the other. Most of the time, they break together, but occasionally, just the outer one will break and then later the inner one will. If you think your water broke, but you do not continue to leak fluid, this might be what has happened. Another theory is that sometimes the baby's head will come down and plug up the hole, stopping the water from leaking, but that one can usually be easily fixed by changing position. Stand up, sit down, lay down, do some yoga poses. When you stand back up again, if your water is broken, you should get some indication of a leak.
What to do if it IS your water?
Call your doula and your care-provider. Remember every birthing practice has different rules on this. Some want to induce five or six hours after a water break (if you aren't having contractions already, that is) others will wait 12, others 24 or more. In some parts of the world, the rule isn't that the baby should be born 24 hours after a water break, its that the baby should be born 24 hours after the first vaginal exam.
Standard of care may be different if you are GBS positive. Some women have had luck going in, getting their IV antibiotics, and then being released again to wait at home as planned until they are in active labor. This is definitely a policy that will be different everywhere you go. If it's important to you, ask!
Do not have sex or try to check yourself if you suspect your water may be broken. It's the act of pushing the germs UP toward the baby that increases your risk of infection. If you are clearly not in labor yet, and you are sure your water is broken, there's no rule that says you have to let your care-provider check you at that point either. Why introduce more risk?
If this happens to you (remember, only about 10 percent of labors begin with a water break) then you have a lot of choices to make. Do you induce? Wait and see? Try to get things started more naturally? Talk with your partner, your doula and your care-provider to figure out what will work best for your situation.
*If the liquid in question is green or brown, or has a foul smell, call your care-provider ASAP