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Current sex pre-selection methods.


 Desire for a male child is common in many countries and cultures. It has been argued that development of a practical and reliable method of allowing parents to choose the sex of their children would reduce family size, and consequently, population growth. There are currently 2 methods of preselection of sex: one preselects the sex before conception by either preventing or facilitating ovum fertilization by the X-bearing or Y-bearing spermatozoa, and the other is selective pregnancy termination. However, current laws and medical ethics in many societies allow selective termination only in cases of serious sex-linked diseases such as muscular dystrophy. Techniques for influencing the sex ratio by altering the X and Y chromosome balance include separation of the ejaculated spermatozoa into X- and Y-enriched fractions before insemination, and altering the vaginal condition. Methods of altering the vaginal condition attempt to influence the sex ratio by changing or choosing the prevailing conditions in the female genital tract which favor 1 or the other sperm type. Timing of insemination (before or after ovulation) is the key concept, and to a lesser extent, certain coital positions. Since 1978, at least 20 studies have been reported to have differential effects on the sex ratio, depending on time of insemination in the reproductive cycle. However, most of the studies have poor methodology and their results are conflicting. Another recently proposed technique is by dietary manipulation. The rationale of the dietary method appears to be attempts to change the ionic milieu of the genital tract of the conceiving female. So far, all these methods have proved to be ineffective and impractical. Currently, not much is known about the basic physiology of sperm at and after ejaculation in a woman and their subsequent interaction with the ionic and hormonal milieu of her genital fluids. It appears unlikely that parents can preselect the sex of their child with certainty by an available technique other than selective abortion.
