How can I determine the sex of my baby?

With conception
While there are many ideas and anecdotal stories in actuality there is no reliable way of making sure your baby is going to be of a particular sex when planning your pregnancy. No approach such as what you eat or timing of sexual intercourse in the menstrual cycle, etc has been proven to be reliable. It is the male sperm that determine sex rather than the female egg. In some male families there is a predisposition to one sex or other. But even then there have been exceptions.

Sex determination after conception
Besides the CVS or amniocentesis which is not done purely for determining the sex of the baby, the most reliable way of determining your baby's sex is through ultrasound scan. The best time to do this is at the fetal morphology scan which is done at about 18 to 19 weeks gestation. Such scan are more accurate  of determining boys. About 60% of couples want to find out the sex at that scan and 40% don't want to know the sex until after the baby is delivered.

Other approaches have been tried over the years. While they may be fun to do they have no proven accuracy.