When one of the five T4 thyroxine tests is low in a pregnant woman, a specific analysis is needed to determine if it is normal. T4 thyroxine can be used to help determine the presence of thyroid disease. T4 alone is not enough to determine disease, but needs to be combined with the results of triiodothyronine (T3) and thyroid stimulating hormone (TSH). If the pregnancy test result shows that the T4 is a little bit low, but the T3 and TSH levels are normal, there is no need to worry too much in this case, so you should go to your labor and delivery on time and follow the doctor’s instructions for regular checkups of your thyroid function. If the result of pregnancy test shows that T3 and T4 are lower and TSH level is higher, this situation suggests that the pregnant woman may have hypothyroidism. If the results of thyroid function test are abnormal, it is recommended to consult a doctor in time to clarify the cause of the disease and carry out targeted treatment or therapy.