Choosing the right time If you want to have a boy, choosing the right time is very important. First of all, the first 14 days of a woman\’s pregnancy cycle are the most fertile period. Having sex during this time can increase your chances of conception. Secondly, having sex on the third day of the fertile cycle increases the chances of fertilizing a male embryo. In addition, male reproductive organs are sensitive to high temperatures, so it is best to avoid exposure to high temperatures.