Whether you're trying to get pregnant, or trying not to, it's important to understand indicators of pregnancy because each symptom may be related to something other than pregnancy.
Here's a list of some of the most common first signs that you may be on your way to motherhood. You may experience all, some, or none of these signs that you could be pregnant:
Food Cravings
Food cravings sometimes can be a sign of pregnancy. If cravings are accompanied by some of the other symptoms on this list, it could mean that you might be eating for two (or more)
Darkening of Areolas
If the skin around your nipples darkens, you may be pregnant. Remember, though, that darkened areolas also remain during breastfeeding and other hormonal changes, so darkened areolas on their own are not a reliable sign of pregnancy.
Light Bleeding or Cramping
Implantation bleeding can be one of the earliest pregnancy symptoms when, about six to twelve days after conception, the embryo burrows into the uterine wall. As a result of this, some women will experience implantation spotting - a slight staining of a pink or brown color - as well as some cramping.
Frequent Urination
Once the embryo implants and begins producing the hormone human chorionic gonadotropin (hCG) - the hormone used by pregnancy tests to detect a pregnancy - usually around six to eight weeks after conception - you may find yourself running to the bathroom more often.
Fatigue
Being totally exhausted is a sign of early pregnancy, and can appear as soon as the first week after conception (long before a positive pregnancy test can be performed), but don't necessarily assume you're pregnant just because you're feeling exhausted.
Tender, Swollen Breasts
If you're pregnant, your breasts will probably become fuller and increasingly tender to the touch, similar to the way they may feel before your period, but more pronounced. These changes may begin as early as one to two weeks after conception and may last throughout pregnancy.
Positive Pregnancy Test
A positive home pregnancy test is the most definitive sign that you're in the family way. Most home tests recommend waiting to test until at least the first date of a missed period to ensure that adequate amounts of hCG.
References:
Heidi Murkoff. What to Expect When You're Expecting, 3rd Edition. New York: Workman Publishing, 2002.
Mayo Clinic Website - Early Symptoms of Pregnancy