First-trimester bleeding with falling HCG: don't assume miscarriage.

Family physicians often use quantitative human chorionic gonadotropin (HCG) testing to assess first-trimester bleeding. While we anticipate a range of normal results for any given week in the first trimester, we predict an approximate doubling over 48 hours in a normal pregnancy during the first trimester. Human chorionic gonadotropin tends to peak at about 10 weeks’ gestation before declining and stabilizing. When HCG levels plateau prematurely or fail to rise as expected, we consider that the pregnancy might not be viable. This case report points to a wide range of normal values for HCG rate of rise and time to peak, making interpretation based on HCG activity alone challenging for family physicians.