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.
How Early Can I Test for Pregnancy? A home pregnancy test determines pregnancy through the detection of the hormone hCG in a urine sample. With most home pregnancy testing products, the âreaction timeâ of the test is a minimum five minute interval to verify a negative result for pregnancy.