hCG levels ramp up quickly in the early weeks of pregnancy. The range for women in their third week of pregnancy is 6 to 71 mIU/mL, compared to 10 to 750 mIU/mL in the fourth week and 217 to 7,138 mIU/mL in the fifth week. Levels continue rising from there until they peak between the eighth and 11th week of pregnancy and then decline and level off. 4
A quantitative hCG blood test can provide an accurate read-out week by week (or even day by day). When taking multiple tests over the course of several days, you and your doctor can detect if your levels are increasing or decreasing. This can help determine if a chemical pregnancy (i.e., early pregnancy loss occurring shortly after implantation), ectopic pregnancy (i.e., non-viable pregnancy in the fallopian tubes or elsewhere outside the uterus) or a miscarriage has occurred. A urine test, on the other hand, only determines whether hCG is present in urine in any detectable amount.