The Chinese pregnancy calendar, also referred to as the Chinese gender chart, allegedly predicts the gender of a baby based on the mother's lunar age and the month of the baby's conception. To use the chart, the expecting mother must find her lunar age on the chart and then follow that row across to the month of conception.
Each box in the chart is generally colored either pink or blue. A blue box means that the charts predicts the baby is a boy, while a pink box predicts that the baby is a girl.
To use the chart, it is necessary to determine the mother's lunar age, which is different from the age used in Western countries. Individuals born after the Chinese New Year should add one year to their Gregorian or Western age to arrive at their lunar age. Individuals born before the Chinese New Year should add two years to their age.
The use of the Chinese pregnancy calendar spans over 700 years. Originally used only by royalty in Imperial China, the chart's purpose was to ensure the birth of a male heir. Ordinary Chinese citizens began to use the pregnancy calendar after the fall of the Chinese empire.