The start of your pregnancy is actually calculated from the start date of your last menstrual period (LMP), or day 1 of your cycle. Given this method of calculation, your pregnancy is measured in what is termed gestational weeks, as opposed to being measured from the actual day of conception. Counting from the first day of your LMP, there are 40 gestational weeks of pregnancy. Assuming that you have a 28-day cycle, in gestational weeks 1 and 2, your baby is waiting to be conceived. On day 14, and at the start of gestational week 3, your baby has just been created. By the end of gestational week 3, the actual age of your baby is one week. Please remember that your baby will come when it is ready, so this result is an estimate only. Be sure to consult your healthcare provider to determine your correct due date.