1. Super pregnancy test sticks work When you get the pregnancy test and press the "ON" button with your hand, it sends a high-frequency sound wave called an ultrasound through the Transducer. The probe of the pregnancy detector must have proper ultrasound with the sow. ''skin contact''. Skin-to-skin contact is better when you apply some oil to the sow skin and probe surface. The pregnancy detector will make a short beep if there is better skin contact and the "ON" button is pressed. . The sow's uterus fills with amniotic fluid during pregnancy. The response occurs when the ultrasound comes into contact with the amniotic fluid in the womb. These ultrasonic responses are received with a continuous sound (the length of the sound) produced by the pregnancy detector to indicate that we know if the sow is pregnant. 2. Super pregnancy test results Only intermittent sounds (no continuous long sounds) = ''The sow is not pregnant'' intermittent sound with continuous sound = ''sow pregnant'' For accurate test results, testing can be done as early as 18 days after sow breeding. At the latest no later than 75 days after the sow is served. Tests performed 18 days after breeding should be repeated 30 days later to ensure accuracy. Test Results.