*HCG is detectable in the blood serum of approximately 5% of pregnant women by 8 days after conception, and in virtually all the rest by 11 days. HCG rises progressively from conception. Levels double on the average, every 30.9 hours until values reach 6500 mIU/ml. Afterwards, HCG will double every 96 hours. After that the rate of rise becomes individualized, peaking between the 60th and 70th day (9 to 10 weeks) Of Last Menustral Period. HCG decreases slightly between the 12th and 16th week post LMP, and then remains constant until birth. 

*Levels for normal pregnancy fall within the following wide ranges. You will note a discrepancy between the ranges of normal in the table. The actual levels can vary widely, and is not as significant as the amount and rate of rise, particularly before 10 weeks.

*A blood serum level of less than 5 mIU/ml (5 IU/L) can be considered negative and anything above 25 mIU/ml (25 IU/L) positive for pregnancy. If you are unsure, repeat the test in two days to see if there is an upward trend, which indicates pregnancy.

* At 14 DPO, the average HCG level is 48 mIU/ml, with a typical range of 17-119 mIU/ml.

* At 15 DPO, the average HCG level is 59 mIU/ml, with a typical range of 17-147 mIU/ml.

* At 16 DPO, the average HCG level is 95 mIU/ml, with a typical range of 33-223 mIU/ml.

* At 17 DPO, the average HCG level is 132 mIU/ml, with a typical range of 17-429 mIU/ml.

* At 18 DPO, the average HCG level is 292 mIU/ml, with a typical range of 70-758 mIU/ml.

* At 19 DPO, the average HCG level is 303 mIU/ml, with a typical range of 111-514 mIU/ml.

* At 20 DPO, the average HCG level is 522 mIU/ml, with a typical range of 135-1690mIU/ml.

* At 21 DPO, the average HCG level is 1061 mIU/ml, with a typical range of 324-4130mIU/ml.

* At 22 DPO, the average HCG level is 1287 mIU/ml, with a typical range of 185-3279mIU/ml.

* At 23 DPO, the average HCG level is 2034 mIU/ml, with a typical range of 506-4660mIU/ml.

* At 24 DPO, the average HCG level is 2637 mIU/ml, with a typical range of 540-10,000 mIU/ml