1 The heart's internal pacemaker regulates and times the beating of the heart via electrical signals.  Electrical signals start at the SA node, causing atria contraction, and then move on to AV node, delaying electrical impulses to allow blood from the atrium to fill the ventricles.
With the First Response new Early Response Twist Pregnancy Test, you can test as early as 6 days before your missed menstrual period. This is the only test that allows you to find out this early, as it is sensitive enough to capture the very scant amounts of the pregnancy hormone.
That is to take a pregnancy test (or have your doctor perform a pregnancy test.) Most pregnancy tests can be taken by two weeks after having sexual intercourse. Pregnancy tests work by monitoring the HCG in your body. This is a pregnancy hormone that is only present when you are pregnant.