Thyrotropin 3.98 mIU/L in pregnant women usually does not require medication and care should be taken not to self-medicate. Thyroid stimulating hormone value is the most sensitive indicator for the diagnosis of primary hypothyroidism, and the normal serum thyroid stimulating hormone is between 0.35 and 5.5 mIU/L. Therefore, it is normal for pregnant women to have a thyroid stimulating hormone of 3.98 mIU/L, and it is usually not necessary to take medication. Therefore, a pregnant woman’s thyrotropin 3.98mIU/L is normal and usually does not require medication to avoid adverse effects of drugs on fetal growth and development. Meanwhile, newborns, pregnant women, and low iodine diets may result in slightly higher thyrotropin levels, but if they are not accompanied by uncomfortable symptoms, there is no need to be overly concerned. If the thyroid hormone value of pregnant women continues to rise and is accompanied by uncomfortable symptoms, we should be alert to primary hypothyroidism, exogenous thyroid hormone-producing tumors and other diseases. It is recommended that women adjust their mindset during pregnancy and follow the doctor’s instructions to attend obstetric checkups on time in order to monitor the growth and development of the fetus. Pay attention to the rationality of daily diet, should also be appropriate exercise.