Hello, and I hope I can help you today. Over-the-counter pregnancy tests check for pregnancy hormone in your urin, however the results are absolutely not reliable in diagnosing the length of gestation. The reason for this, is that the amount of pregnancy hormone in your urine, depending upon how much water you drank, is variable and is not a reliable way to confirm the dating of your pregnancy. However, what the box is explaining is the way that we routinely as physicians calculate the due date for someone s pregnancy. As a convention, the due date for pregnancy is calculated based on the first day of the woman s last menstrual period. The pregnancy test measures the amount of pregnancy hormone, theoretically, from the date of conception. In women with a 28 day menstrual cycle, ovulation typically occurs at 14 days after the start of your period, so, that is why your doctor will refer to your pregnancy as two weeks further along than the pregnancy test. So, in the meantime, I would not worry too much about calculating your due date. When you see a doctor for the first time for this pregnancy, he or she will explain how we determine your due date. Obstetricians generally recommend that you see a doctor for your first prenatal visit at around 6 to 7 weeks gestation (from the first day of your last menstrual period) In the meantime, please begin taking a prenatal vitamin supplement, stop drinking alcohol, and wait and see what happens. As long as you have no bleeding, it is safe to assume that you have a healthy pregnancy and when you see her doctor for the first time they will confirm your due date with an ultrasound examination. I hope I was able to clarify the difference between conception and pregnancy dating based on your last menstrual period. In addition, I hope that my advice was helpful. Best wishes for the rest of the pregnancy, Dr. Brown.