The Chinese Baby Gender Prediction Chart predicts baby gender using woman's Chinese age and conception month. That Gender Calendar's a statistic chart made by Chinese in the Ching Dynasty. This is nothing do with Chinese astrology.
Chinese Astrology uses Five Elements, Metal, Water, Wood, Fire and Earth, relationships to predict people's fortune, career, wealth, reputation, marriage and family members. Five Elements have the Mother-and-Child relationship.
If you are a woman and want to know which element represents your child, then you have to find out which element represents you from the Chinese Astrology Birth Chart first. This requires your birthday to build your astrology natal chart. If women know their son's element, then women will know which year they can have better chance to give birth a baby boy.