Kapha dosha overproduces rasa dhatu. The rasa dhatu is reflected in the quality of the endometrium or the lining of the uterus. Kapha dosha is comprised of earth and water, the water component of kapha brings a great amount of fluidity to rasa. On the other hand, the earth gives a little bit of stability and stagnation.
A kapha person may have a harder time before the period begins, they may feel stagnation at the onset of their period. A feeling of heaviness may ensue before the time of menstruation. When the period begins they may have moderate flow but it may have a much longer duration lasting 7 to 9 days. This is because of the amount of tissue that they have produced but they need to move out.
Kapha dosha lacks the heat of pitta, so the menstruation is not as intense however the duration may be longer, they may pass moist clots along with menstruation because of the qualities of water and earth. Kapha dosha may impact the formation of shukra, now we know that shukra is reflective of all the dhatu that have gone before, when kapha dosha over produces, it can create a level of stagnation in the body and sluggishness in the tissues. In this scenario, it is possible that the periods may be regular but with a sluggish start. Kapha dosha typically produces healthy egg, but they may experience stagnation in their system that could block fertility.
Usually kapha dosha produces high quantity of tissue but of poor quality. When that comes to shukra dhatu we only have one shukra that is being produced every month. In this case, just one egg is being produced but that is also reflective of the fluids that are travelling with the egg itself.
Kapha dosha may have a harder time with fertility if they have stagnation or too much fluid travelling with the egg because that can interfere with conception.