Serum is not necessary in human in vitro fertilization, early embryo culture, and transfer

Human in vitro fertilization (IVF), embryo culture (EC), and embryo transfer (ET) are commonly performed in various media supplemented with blood serum. To determine whether serum is really necessary, the results of IVF, EC, and ET were compared by using two types of media: B2 medium supplemented with human cord serum and B3 medium without any serum. B3 medium is similar to B2, except that it contains 1% pure controlled human serum albumin in place of 1% bovine serum albumin. We did not observe any difference between the results obtained by using B2 or B3 at any phase of IVF, EC, and ET processes. Both media give an overall evolutive pregnancy rate of about 16%. B3 medium with serum seems to increase slightly the cleavage speed. Our results indicate that there are no positive effects when serum is used for human IVF-ET. To avoid serum supplementation is of evident interest for the homogeneity of the results. This will also lead to a better understanding of human early development and control of the egg quality by metabolic analysis of the media following in vitro EC.