Breastfeeding without medication for hypothyroidism will aggravate the mother’s hypothyroidism, and she may suffer from hypothyroidism symptoms such as swelling and fear of cold, which will damage her health. For the baby, because the baby’s own thyroid function after birth has been more perfect, can secrete and synthesize thyroid hormones, the baby may not have too much impact. But for the mother, the impact is greater, if not timely medication treatment, the body will be in a low metabolic state, there will be hair loss, swelling, fear of cold and other symptoms, and severe mucous edema coma. Hypothyroidism patients in the breastfeeding period should also eat levothyroxine sodium and other drugs in a timely manner to replace the treatment, and at the same time to regularly go to the hospital to review the thyroid function, under the guidance of the doctor according to their own thyroid function to adjust the dose of medication, shall not be unauthorized discontinuation of medication, in order to avoid the adverse consequences.