Regular menstrual cycles are good indicators of normal ovulation. When ovulation proceeds on a regular pattern, this is reflected in regular menstrual cycles. Women who have irregular periods often find it difficult to conceive. In Chinese medicine, irregular periods are sub-classified into early periods, late periods, light periods and heavy periods. The common patterns for infertility due to irregular periods in Chinese medicine are liver qi stagnation, kidney deficiency, blood heat, and blood stasis.