Progesterone is still active after 12 weeks, inhibiting contractions and promoting breast follicle development. Progesterone levels rise steadily with each week of pregnancy, with 6 weeks of pregnancy coming from the corpus luteum of the ovary, and mid-pregnancy being secreted by the placenta. Progesterone in early pregnancy is favorable for embryo implantation, and will continue to prevent uterine contractions after 12 weeks of pregnancy, so that the uterus is in a state of rest, which is conducive to the maintenance of pregnancy. At the same time, progesterone also promotes the development of breast follicles in preparation for breastfeeding. After 12 weeks of pregnancy, you should also pay attention to appropriate rest, can not be too tired, appropriate increase in diet and nutrition, in order to meet the needs of fetal growth and development. Also under the guidance of the doctor to carry out a moderate amount of physical exercise, in order to ensure appropriate weight gain during pregnancy, which can reduce the risk of pregnancy, but also conducive to natural delivery.