Implantation Bleeding

Implantation bleeding can be one of the earliest pregnancy symptoms. About 6-12 days after conception, the embryo implants itself into the uterine wall. Some women will experience spotting as well as some cramping. Other Explanations: Actual menstruation, altered menstruation, changes in birth control pill (switching brands), infection or abrasion from intercourse.

Delay/Difference in Menstruation

Delayed or missed menstruation is the most common pregnancy symptom leading a woman to test for pregnancy. When you become pregnant your next period should be missed. Many women can bleed while they are pregnant, but typically the bleeding will be shorter or lighter than a normal period. Other Explanations: Excessive weight gain/loss, fatigue, hormonal problems, tension, stress, ceasing to take the birth control pill or breast-feeding.

Fatigue or Tiredness

Feeling fatigued or more tired is a pregnancy symptom which can also start as early as the first week after conception. Other Explanations: Stress, exhaustion, depression, anemia, common cold or flu, or other illnesses can also leave you feeling tired or fatigued.

Nausea/Morning Sickness

This well-known pregnancy symptom will often show up between 2-8 weeks after conception. Some women are fortunate to not deal with morning sickness at all, while others will feel nauseated throughout most of their pregnancy. Other Explanations: Food poisoning, stress, or other stomach disorders can also cause you to feel queasy.

Backache

Lower backache may be a symptom that occurs early in pregnancy; however, it is common to experience a dull backache throughout an entire pregnancy. Other Explanations: Impending menstruation, stress, other back problems, and physical or mental strains.

Headaches

The sudden rise of hormones in your body can cause you to have headaches early in pregnancy. Other Explanations: Dehydration, caffeine withdrawal, impending menstruation, eye strain or other ailments can be the source of frequent or chronic headaches.

Frequent Urination

Around 6-8 weeks after conception, you may find yourself making a few extra trips to the bathroom. Other Explanations: Urinary tract infection, diabetes, increased liquid intake or taking diuretics.

Darkening of Areola

If you are pregnant, the skin around your nipples may get darker. Other Explanations: Hormonal imbalance unrelated to pregnancy or may be a leftover effect from a previous pregnancy.