In my Shiatsu sessions with women I will often work on an channel called 'The Heart Uterus' channel'. This meridian connects the heart to the uterus and I access it through the front of the body. Menstrual blood is seen as excess blood that is sent down to the uterus from the heart through this Heart-Uterus channel. The heart-uterus meridian runs directly between the heart and the uterus, nurtures the uterus with blood and Ki (energy).
The uterus provides a nurturing, balanced, moist interior environment for the potential fetus, whilst regulating the menstrual cycle. It's functioning is influenced by many other channels, including the heart, but the heart's role is to supply it with qualitative, nurturing blood, so that it can provide a nurturing environment for the baby.
Traumas that affect the heart will affect and traumatise the uterus, and prevent the smooth flow of blood and Ki to the uterus. We can see this in delays and skipping of menstruation when stress or disruption in our lives are experienced, such as jet lag, heart break, stressful situations or changes in our environment.