The most obvious indication that you might be pregnant is that you miss one or more periods in a row. However, our bodies give us many other subtle clues that a baby is on the way -- sometimes even before you realize your period's gone missing.
Some women experience implantation bleeding, which occurs when a fertilized egg implants in the uterus. (It's much lighter than menstrual bleeding, and lasts only a day or two). Other common signs include nausea (yep -- it's the start of morning sickness), needing to pee all the time, constipation, and food cravings -- especially for carbs. Very early in pregnancy, other symptoms often mimic those of PMS, like cramps, bloating, headaches, mood swings, or sore breasts and nipples. Fatigue's a big one too -- it's common for new moms-to-be to feel totally wiped out for no apparent reason.
If you think you might be pregnant, take a home pregnancy test. This works by identifying the presence of the hormone human chorionic gonadotropin (hCG) in your urine -- your body starts releasing it soon after you conceive. See a positive result? Congratulations! It's time to call your doctor to schedule the first of many prenatal visits. See a negative result? If you still don't get your period after a few days, try testing again. Sometimes testing too early means your body hasn't yet produced enough hCG for the test to detect.