The older that such fish become, the more mercury they may have absorbed. Anything that eats these fish within the food chain also consumes the higher level of mercury that the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher
The goal, then, when it comes to having a boy is to increase the likelihood that a Y chromosome sperm reaches the egg first. Many medical researchers believe that Y chromosome sperm are faster swimmers, but that X chromosome sperm have more endurance.
Smoking: Smoking significantly increases the risk of infertility in both men and women, and it may undermine the effects of fertility treatment. Smoking during pregnancy increases the chance of pregnancy loss. Passive smoking has also been linked to lower fertility. Alcohol: Any amount of alcohol consumption can affect the chances of conceiving.