1, early embryonic embryonic tissues encounter mechanical damage, etc. During embryonic development, the control gene segment is misconfigured and tissue differentiation develops abnormally. 2, environmental pollution, drug stimulation and adverse factors lead to abnormal proliferation and expansion of the vascular network in the embryo within 3 months. Such as hormone-containing drugs or food, causing excessive estrogen. 3, trauma factors. Radiotherapy, viral infection, trauma, surgery, vascularity reaction after bleeding can be induced.