Usually, breastfeeding pregnancy can stop producing milk around the third month of pregnancy. After a lactating pregnancy, the nutrients in the pregnant woman’s body are mainly supplied to the fetus in the uterus to promote its growth and development. Secondly, the secretion of estrogen and progesterone as well as lactogen will change after lactating pregnancy, which will easily lead to a decrease in the amount of lactation. Usually in the third trimester, the body’s endocrine secretion is already at a standard pregnancy endocrine level, and basically there is no milk production. Milk belongs to the nutrition in the mother’s body, if too much is secreted and sucked out too much, it may cause the mother’s nutrition to be insufficient and affect the development of the fetus. Therefore, after breastfeeding pregnancy, it is recommended to stop breastfeeding to prevent the lack of nutrients in the body from affecting the growth and development of the fetus. In addition, frequent stimulation of the nipple may also cause contractions.