Whether or not you can usually detect pregnancy on the fifth day of transfer depends on the type of embryo transferred; blastocysts that have been cultured for five days are likely to be detectable, and cleavage stage embryos that have been cultured for three days are not detectable in most cases. There are two types of embryos, blastocysts and cleavage stage embryos. If a blastocyst stage embryo that has been cultured for five days is transferred, it is possible to test it on the fifth day after the transfer using an early pregnancy test strip, which may show a slight red color at the detection line, indicating a weak positive, but the accuracy is not very high. If a three-day cultured cleavage stage embryo is transferred, a test on the fifth day of transfer using an early pregnancy test paper will not detect pregnancy, and the blood HCG is usually not up to the standard of detection. It is not recommended to test on the fifth day of transfer to see if the transfer has been successful, the error rate is higher, it is recommended to test after 10 days of transfer.