Hello There are Concerns when one of three things happen: 1.HCG levels are lower than expected, 2. The rate of HCG increase is slower than expected, or 3. HCG levels begin to drop. Each may suggest the following complications: 1. A low hCG level can mean many number of things. In some cases, it may simply be that the pregnancy date was miscalculated, and you are not as far along as you had thought. Further testing would be needed to determine the cause, which may or may not include a miscarriage, a blighted ovum (where the egg has not attached to the uterus wall), or an ectopic pregnancy (where the egg implants outside of the uterus). 2. Slow-rising hCG levels may also be a sign of trouble in early pregnancy. 3. Dropping hCG levels in the first trimester over the course of two to three days is usually the sign of an impending miscarriage. This is especially true for women experiencing symptoms of miscarriage such as heavy vaginal bleeding. Decreasing levels of hCG in the second and third trimester are usually not a concern. Stress can cause a miscarriage. You could make it happen when it wouldn t have just because you are freaking out about something that hasn t happened yet. Calm yourself down. Think happy thoughts. Hope it turns out alright. Thanks Dr. Tripat