Progesterone is an important sex hormone in the female body, when the level of progesterone in the female body is insufficient, it will cause a series of clinical symptoms. For women during pregnancy, the most important danger of insufficient progesterone is that it affects the state of the endometrium, which is not conducive to the development of the fetus, and there are symptoms of preeclampsia or miscarriage, and appropriate supplementation of progesterone can help to preserve the fetus. However, progesterone is not supplemented the more the better, excessive supplementation of progesterone may cause adverse effects, mainly including: 1, excessive supplementation of progesterone, will reduce the muscle sensitivity of the uterine wall of the uterus to the hysteronin, inhibit uterine contraction, is not conducive to the full-term smooth delivery. 2, excessive supplementation of progesterone during pregnancy, may also be the healthy development of the baby, resulting in a potentially adverse impact. In short, any improper use of drugs during pregnancy may jeopardize the health of the mother and child, even when there is a need to supplement the indications of progesterone, should follow the doctor’s instructions for reasonable use of drugs.