A single measurement of hCG cannot be used to determine the gestational age or even to estimate a due date. The laboratory that processes most of the specimens from my office recently stopped giving a reference range as this was completely worthless. The following are the reference ranges previously quoted: 1 week since conception: 5-50 mIU/ML hCG 2 weeks since conception: 20-500 mIU/ML hCG 3 weeks since conception: 500-5,000 mIU/ML hCG 4 weeks since conception: 3,000-19,000 mIU/ML hCG 8 weeks since conception: 14,000-169,000 mIU/ML hCG 12 weeks since conception: 16,000-160,000 mIU/ML hCG So, as you can see, there is a considerable amount of overlap. . A quantitative hCG test (or beta hCG) measures the amount of hCG actually present in the blood. This test will provide an actual number. This test will provide an actual number. When there is a concern about the health of the pregnancy, a single hCG reading is not enough information for most diagnoses.. The levels of beta-hCG (human chorionic gonadotrophin) vary widely at different stages of pregnancy. This hormone prolongs the lifespan of the corpus luteum as well as stimulates production of progesterone..