HCG levels in pregnancy can vary greatly and early fluctuations are normal. In your case, the initial increase was large, which could suggest multiple pregnancy, but the drop from 23.3 to 20.9 may only be fluctuations, which do not necessarily indicate the loss of the embryo. It is important to monitor hCG levels in the following days and consult a doctor who can assess the situation and possibly order an ultrasound to confirm the development of the pregnancy. It is important to remember that many pregnancies develop normally despite early fluctuations in hCG levels.

If you need more personalized advice, you can use teleconsultations here:

https://www.gdziepolek.pl/telekonsultacja/z-ginekologiem