Objective To analyze the changes of serum thyroid stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) levels in patients with abnormal thyroid dysfunction during pregnancy and their relationship with maternal and infant outcomes. Methods Retrospectively analysed the clinical datas of 80 cases patients with abnormal thyroid function admitted to Changzhou Maternal andChild Health Hospital from January 2019 to January 2020, they were divided into the hyperthyroidism group, the subhypothyroidism group, the hypothyroidism group and the transient hypothyroxinemia of prematurity (THP) group according to the pathological types of patients, with 20 cases in each group. In addition, the pregnancy examination datas of 35 healthy women who were examined in the Changzhou Maternal and Child Health Hospital during the same period were selected as the healthy control group. The thyroid hormone levels, premature delivery, delivery method, newborn weight, and newborn Apgar score of the subjects in the healthy control group and the patients in the hyperthyroidism group, the subhypothyroidism group, the hypothyroidism group, the THP group were compared. Results The levels of serum TSH of patients in the hyperthyroidism group were significantly lower than those in the healthy control group, and the levels of serum FT4 and FT3were significantly higher than those in the healthy control group; serum TSH level in the subhypothyroidism group was significantly higher than that in the healthy control group; serum TSH levels in the hypothyroidism group were significantly higher than those in the healthy control group, and serum FT4 and FT3 levels were significantly lower than those in the healthy control group; serum FT3 and FT4 levels in the THP group were lower than those in the healthy control group; the proportion of obstetrical forceps, premature delivery, and cesarean section in the hyperthyroidism group, the subhypothyroidism group, the hypothyroidism group, the THP group was significantly higher than in the healthy control group, and the proportion of normal delivery patients was lower than that in the healthy control group; the newborn weight of the hypothyroid group, the hypothyroidism group were significantly lower than that in the healthy control group (all P <0.05). There was no statistically significant difference in Apgar scores among the 5 groups 5 and 10 minutes after birth (P >0.05). Conclusion Thyroid dysfunction can lead to abnormal levels of serum FT3, FT4 and TSH in pregnant women, which ultimately affects maternal delivery methods and increases the possibility of premature delivery. In addition, hypothyroidism and hyperthyroidism during pregnancy can affect fetal growth and development to a certain extent, leading to the low birth weight of newborn.