Low progesterone in early pregnancy may be caused by poor embryo quality, luteal insufficiency, thyroid dysfunction, insulin resistance and other reasons. 1. Poor quality of embryo: The poor quality of sperm and egg in early pregnancy will result in poor quality of embryo after pregnancy, low increase of human chorionic gonadotropin, and lower value of progesterone in the body, which will result in higher chance of miscarriage of the embryo. 2. Luteal insufficiency: patients with luteal insufficiency will lead to insufficient secretion of progesterone in the body, and there will also be low progesterone. 3. Thyroid dysfunction: the presence of thyroid dysfunction in pregnant women will affect the normal function of the ovaries, and the lack of progesterone secretion in the body will lead to the phenomenon of low progesterone. 4. Insulin resistance: pregnant women have insulin antibodies in their bodies, which will change the progesterone, and there is also a low progesterone during pregnancy. There are many reasons for low progesterone, and it is recommended that you seek medical attention as soon as possible.