Why does false negative blood pregnancy occur then after 2 days positive is it cuz it's unhealthy baby?

Common finding: The pregnancy tests are based on finding a hormonal material made by the new embryo. Until it builds up enough hormone in the blood, it does not reach a level that will turn the test positive. If you test early, it may be negative, and after 2 days, turn positive because it is finally making enough hormone. It does not mean the baby is unhealthy.