A Cheat Sheet to Pregnancy Hormones

Human Chorionic Gonadotropin (HCG)

Human Chorionic Gonadotropin (HCG)

What it does: HCG is the key hormone that's present during pregnancy. It's produced by what ultimately becomes the placenta. Its basic job is to tell a woman's body that there is a life form growing in her womb and that her body needs to build a nest for it. HCG also tells the ovaries to shut off the production line of maturing an egg every month. Levels rise eight days after ovulation, peak at 60 to 90 days and then lower slightly, leveling off for the remainder of the pregnancy. Typically, during the first 10 weeks of your pregnancy HCG levels double every two days. HCG circulates through the body and is eliminated in the urine (which is what over-the-counter pregnancy tests are looking for -- a high concentration of beta HCG in the urine that indicates you are, indeed, pregnant).

The down side: No one is entirely sure what causes morning sickness, but many doctors believe it is most likely connected to your rising HCG levels. Women with higher levels of HCG often experience more nausea and vomiting.