and the effect on Gender
Research supporting Sperm’s effect on gender determination:
All babies begin with an X-bearing chromosome from the egg released by the woman. From there, it is up to the male to determine which gender the baby will become. Often, the question is raised as to whether an individual can naturally have an unequal proportion of X- and Y-bearing sperm cells even if there is a family history of mostly female or male offspring? The answer is NO-
The scientists at MicroSort have performed more than 5,000 analyses of X- and Y-bearing sperm cells prior to sorting and all results have been very close to 50:50. This seems true even when there is a family history of mostly female or male offspring.
Y sperm and lighter and thus, faster
The proportion of X and Y (male) bearing sperm in semen are equal. But male embryos and fetuses have a higher risk of dying in the womb. Consequently, scientists have been trying to find out why there are more male babies. Dr Smits and his team say their work supports the theory that conception depends on how viscous, or “sticky”, the mucus in a woman’s cervix is. The stickier it is, the harder it is for any sperm to get through. But Y bearing sperm are lighter(2% smaller), and swim faster. Therefore, if a woman takes longer to get pregnant, it may be that she has thicker than usual mucus. This would mean it is harder for any sperm to get through, so conception takes longer. And, when it does happen, it is more likely to have a boy because of male sperm’s swimming abilities. Dr Smits said: “Women whose cervical mucus is relatively viscous would not only have more difficulties conceiving naturally, but also have a higher probability of male offspring if they do get pregnant. “This may explain why there is a higher chance, in general, of having boys.”