A more serious presentation is neonatal purpura fulminans, which is when a newborn with protein C or S deficiency suffers massive arterial and venous thromboembolisms with hemorrhagic skin necrosis.

更严重的并发症是新生儿暴发性紫癜，即患有蛋白C和S缺乏症的新生儿出现大量动静脉血栓栓塞及出血性皮肤坏死。