Beta-HCG Test Accuracy: Understanding Results & Timing

Question
i wanna know that is it possible that i am pregnant but my Beta-Hcg-QUANT,(Titer)tests doesnot show it even after more than one month of conception.i had two blood hcg,Quanttests the last one some 40 days after possible conception time but both are negative.so is it possible that these tests  havenot shown them.i would like to have your detailexplination on reliability and accuracy of Beta-Hcg,Quant,Titer tests.

Answer
A Beta HCG will be accurate if it is performed 14-21 days arter conception . The best time to take a Beta HCG is seven days after missing your period. If the results are negative (or less than 5) at that time, you are not pregnant. If you have any doubts, take two Beta HCG tests, 48 hours apart. If there is a doubling of the results in 48 hours, it indicates a viable pregnancy. If there is a halving of the results in 48 hours, it indicates a miscarriage. If the value is consistently less than 5, you were never pregnant.