HCG is a pregnancy hormone. The same one that those little home pregnancy tests look for. FYI, the “early” tests are simply more sensitive and can detect lower levels. A nice chart on the sensitivity of the home tests can be found here.

Once you’re confirmed pregnant, especially if you’re being closely monitored like we are, your doctor will take at least two measurements of your HCG levels. It’s not as much about what the numbers are because they can vary widely (go here for an extensive database of average HCG or “beta” levels in pregnant women). It’s more about making sure HCG levels are increasing at a rapid level. Generally, a woman with a single pregnancy (ie., not twins, triplets, etc.) should have her HCG level approximately double every two days in her pregnancy up to about 18 days past ovulation. After that, it starts to slow down.

In Elizabeth’s case, her HCG level was 695 and then 1495 two days later. Right on schedule and generally a sign that, at this point at least, the weather is hunky dory in Uterusville.