Understanding Low HCG Levels After IVF: What Does It Mean?

Question
Last Period 5/6 IVF retieval 5/19 implated 2 embroyos 5/22. 12 days past 5/19 had hcg level of 4. 14 days past had hcg level 8. Could it be that my embroyo implated late? I am planning a 3rd blood test Monday, looking for 25...but even at 25 am I looking bad?  

Answer
An HCG level less than 5 does not indicate pregnancy.If the  implantation of the embryos was on May 22, a pregnancy test should not be done until 21 days after fertilization which  is not until after June 12. At 4 weeks from insertion of the embryos, the HCG value should be 100-10,000. A level of8 is very low. 23 is still a very low level. You should now be more than 100.