hCG Level Doubling Time Calculator
Enter in your numbers and the doubling time will be calculated automatically.
http://www.baby2see.com/preconception/hcg.html
Ultrasound findings after five or six weeks of pregnancy are much more predictive of pregnancy outcome than are hCG levels. You won't expect to see a gestational sac or the fetus until the hCG level reaches at least 1,200 mIU/ml.
You can use the calculator above to calculate the doubling time of two beta hCG samples by entering the values of the blood tests and the number of days between the tests.
The hCG levels will usually double approximately every 48 hours [ 2 days ] for the first four weeks of pregnancy.
As pregnancy progresses the doubling time increases. By 6 to 7 weeks gestation beta hCG levels may take as long as 84 hours [ 3½ days ] to double.
The beta hCG may take more than 48 - 72 hours [ 2 to 3 days ] to double in 15% of normal intrauterine pregnancies.
About 17% of ectopic pregnancies have normal doubling times.
Twins or Higher Pregnancies:
Twin pregnancies tend to show higher HCG levels on a given day of pregnancy. Twin HCG levels fall within the reported range of singletons, so, you can not assume anything based on the level alone. A higher level on a given day does increase your chances for twins, but there is no level above which you are guaranteed twins.
Your HCG Levels:
Check with your physician about your own levels. In addition, do not try to draw conclusions on either the viability of your fetus or the possibility of multiples, unless you have a series of HCG tests done that clearly indicate a pattern.