About the Simulation Calculator

Home Pregnancy Tests are qualitative, answering Yes/+ (pregnant) or No/- (not pregnant). They do so by comparing the amount of the pregnancy hormone (ie. hCG) in the sample to the amount measured by the test. For example, if a test's sensitivity is 40 mIU/ml, a sample with 40 mIU/ml or more will test postive, and a sample with less than 40 mIU/ml will test negative.

When it comes to doubling, what your actual hCG level is on the day of implantation obviously affects how quickly it increases to a level where a qualitative urine-based home pregnancy test would show positive.

Therefore, to simulate doubling, a starting hCG level, representing what would be present at implantation, is needed. This, however, is one of our cycle conundrums - almost impossible to know for sure.

Luckily, studies give us some good ranges. Many clinical charts indicate that levels during the first week after implantation is between 5mIU/ml to 50mIU/ml, whereas others, including a study specifically designed to determine hCG levels in the first week after implantation, showed levels of less than 1 mIU/ml a day after implantation.

You can choose the initial hCG level which is used for doubling, using the Initial Level drop-down. By simulating with different initial levels, combined with the calculator's 2 and 3 day doubling rates, you can see how it influences when your hCG would likely rise to the level detectable by home pregnancy tests.

With so many variables in the early stages of pregnancy - when implantation will occur, what your starting pregnancy hormone level is, and how quickly it will double - this calculator is an excellent way to view the possibilities, as you wait to see if this is your BFP cycle. Baby Dust!