There are several possible reasons for high TSH during pregnancy: 1. The body’s demand for thyroid hormone increases during pregnancy, and the basal metabolic rate of individuals increases, resulting in high TSH. This is a normal physiological reaction as long as it is within the normal range. 2. Pregnant women develop hypothyroidism. The excessive consumption of thyroid hormones in the body leads to overproduction of thyrotropin TSH and hypothyroidism. 3. Endocrine disorders. During pregnancy, the relative ratio of estrogen and progesterone in the body changes constantly, and if endocrine disorders occur due to emotions or living and eating habits, it will easily lead to high TSH. The increased demand for substances or secondary loss of appetite can easily affect the normal growth and development of the fetus. 4. Premature birth. The presence of low A and high TSH during pregnancy is often a precursor to preterm labor or even miscarriage.