The best time to measure pregnancy is 25 days to 30 days after breeding, because the gestational sac is the most obvious and presents a regular round black hole, which is the easiest to judge. As the gestational sac develops, the gestational sac becomes irregular. It is not as easy as the previous judgment, but it is obvious that it is different from the empty pregnancy image. When the sow's gestation days reach 70 days, the piglet's bones are calcified. At this time, the animal pregnancy scan image shows an intermittent arc of broken lines. This is the spine of the piglet,and based on this to judge whether pregnant.