The typical pregnancy test checks a woman's blood or urine for the presence of a substance called human chorionic gonadotropin (hCG). This is a hormone made by the placenta. When this hormone is present, it usually indicates that the woman is pregnant. Home pregnancy tests can give false positive or false negative results. If you suspect you could be pregnant, you can see your doctor for a pregnancy test. The doctor may perform a pregnancy test on your blood or urine. Your doctor can give you a blood pregnancy test as early as 11–14 days after ovulation. To perform a blood pregnancy test, the doctor draws blood from a vein in your arm. This blood is sent to a laboratory for testing. The results of most blood pregnancy tests take at least a couple of days. The laboratory then advises the doctor of the result.

Other reasons for a missed period
Pregnancy is not the only reason for a missed period. Other possible reasons include Breastfeeding, Emotional Stress, Severe Weight Loss, Server Dieting and Exercising and Obesity.