The time it takes for a pregnancy test to become negative following a miscarriage depends upon the gestational age at the time of miscarriage. For any pregnancy, whether it ends at term, preterm, or in miscarriage, a urine pregnancy test should be negative after six weeks. If it is not, there are three concerns:or any pregnancy, whether it ends at term, preterm, or in miscarriage, a urine pregnancy test should be negative after six weeks.