Materials and Methods: A total of 60 mice were obtained from Pasteur Institute, Karaj, Iran. Female mice were stimulated to ovulate with PMSG hormone, and the oocyte was released by human chorionic gonadotropin (hCG) hormone. Sperms were collected from the male mice. In vitro fertilization (IVF) was performed in the completely sterile conditions in a control culture medium with pH=7.4. Then six experimental groups, three experimental groups with sodium bicarbonate as well as three experimental groups and the embryos, were transferred from the multicellular stage (the blastocyst) to pseudopregnant mice.

Results: Three groups treated with sodium bicarbonate with different pHs were significantly different from the control group regarding the percentage of the born male fetuses (P ≤ 0.05); however, this difference was not significant between the sodium bicarbonate groups with different pH (P ≥ 0.05). Among the groups receiving calcium bicarbonate treatment, only the average pH level of male infants at 7.7 demonstrated a significant distinction when compared to both the control group and the remaining treatment groups (P ≤ 0.05).

Conclusions: Using sodium bicarbonate and calcium bicarbonate as well as adjusting the pH of the oocyte and sperm fertilization environment based on them may have been a safe and cheap method to determine the sex of a fetus.