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HCG Pregnancy Calculator

HCG Graph and Doubling Time Calculator

What is HCG?

HCG (human chorionic gonadotropin) is the pregnancy hormone. HCG is produced by pregnancy cells (trophoblast) that invade the uterine lining and develop into the placenta. HCG stimulates the ovary to produce progesterone. Progesterone is the hormone that maintains the endometrial lining of the uterus. In the normal menstrual cycle, progesterone production by the ovary only lasts for 2 weeks after ovulation and when the progesterone level falls menstruation begins. If pregnancy occurs, however, HCG keeps progesterone high and therefore prevents menstrual bleeding.

Pregnancy tests

Pregnancy tests detect HCG. Urine pregnancy tests usually can detect HCG by 14 to 16 days after ovulation. Blood pregnancy tests are more sensitive and can detect HCG within 10 to 12 days after ovulation. Qualitative tests for HCG (urine or blood tests) are those that report pregnancy results as either positive or negative. Quantitative tests measure the actual level of HCG in the blood stream. When you become pregnant after tubal reversal surgery, quantitative HCG assays should be performed. As soon as you have a positive home pregnancy test (a qualitative test), report your pregnancy to us and to your local physician. Quantitative serum HCG levels should then be checked twice a week until they reach 1500-2000 mIU/ml, at which time a vaginal ultrasound exam should be performed to look for the gestation sac within the uterus. This is Dr. Berger’s recommended protocol for early pregnancy monitoring.

HCG doubling time

In a normally developing singleton pregnancy, quantitative serum HCG levels double every 2-3 days during the earliest weeks of pregnancy. This HCG calculator can be used to determine the doubling time of your HCG levels.

First HCG Level:  
Second HCG Level:  
Days Between Tests:  


Measuring and interpreting HCG blood levels is the best way to monitor the development of a pregnancy in the earliest weeks. In a normally developing pregnancy, serum HCG levels double every 2 to 3 days. When serum HCG reaches 1500-2000 mIU/ml, a vaginal ultrasound exam should show a gestation sac in the uterus.

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