I agree with Layla. My HCG levels were very low at the beginning of pregnancy and the doctor wanted to wait a week to check again in case the reason they were low was because I was going to have a miscarriage. A week later they had gone up, but not as much as she would have expected. The doctor sent me for two more blood tests in the following three weeks and the results were always on the lower end of normal and really worried me unnecessarily, but all is ok now.