What are the body\’s reactions to reduced progesterone levels? Progesterone is an important hormone that has a crucial impact on the growth and development of the lining of the uterus and the fetus. Once progesterone levels drop, it causes related body reactions, which vary from case to case. This article will elaborate on four aspects. 1. Emotional and mental changes Progesterone is a hormone synthesized in women’s bodies. It has a great impact on women’s emotional and mental states. Once progesterone levels are reduced, women\’s mood changes will be greater. Common manifestations include: mood swings