A first-trimester serum TSH in the 4-10 mIU/L range is associated with obstetric complications in thyroid peroxidase antibody-negative women.

In TPOAb-negative pregnant women, a first-trimester serum TSH level ranging from 4 to 10 mIU/L is significantly and independently linked to an increased uterine artery pulsatility index as well as to negative pregnancy outcomes such as pre-eclampsia, SGA and gestational diabetes.