When you think you might be pregnant, you want to know as soon as possible. So you may do what many women do and run out to the drugstore a few days after the alleged conception to pick up a pregnancy test. But how do you know you're getting accurate results? The first mistake many women make is testing too early. Pregnancy tests detect the presence of hCG - a hormone produced when the placenta starts developing. If the fertilized egg hasn't implanted on the uterine wall yet, then you may get a false negative and then test positive a few days later. It can take up to 9 days for the fertilized egg to attach to the uterine wall, so taking a test less than 10 days after conception may not yield an accurate result. Variations in the test's sensitivity, being unsure when the egg could've implanted and irregular menstrual cycles can all skew test results. The best results are gained when urine is tested in the morning when hCG has had a chance to become more concentrated.
If you do get a positive test, then you should go to the doctor's office, where they'll make sure you're pregnant by doing either an ultrasound or another test to measure the presence of hCG. A qualitative hCG test will answer the question "Am I pregnant?" with a simple yes or no. A quantitative test, given by a doctor, might be used if a woman has undergone fertility treatments and answers the question "How pregnant am I?" It can detect very low levels of hCG early on in the pregnancy, and it may be used if the pregnancy is high-risk or to test for an ectopic pregnancy, or one that's formed in the fallopian tube instead of the uterus. If you're not sure about your results at home, then it's always good to retest and then share the results with your doctor, who can rule out any problems and advise you along the way.