Preconception selection of sex in man.

The determination of sex is influenced by ionic factors. In man, ionic imbalance is responsible for the sex ratio in at least 80% of cases, the possible mechanism being one of selective fertilization. These facts constitute the scientific basis for the medicodietary method of selecting sex. The intervention of ions in ovarian metabolism is obtained by controlling the diet of the woman, the decisive factor being the ratio of K+ + Na+ to Ca2+ + Mg2+ in the daily diet. High values of this ratio lead to boys, and low values to girls. Using this method since 1970 in 47 births, only 7 of them failed to produce the expected sex. The interactions and the causes of failure are analyzed.