Association of Isolated Hypothyroxinemia and Subclinical Hypothyroidism With Birthweight: A Cohort Study in Japan.

Pregnant women with isolated hypothyroxinemia and subclinical hypothyroidism in the first trimester have an increased likelihood of SGA. Screening and careful perinatal checkups for isolated hypothyroxinemia and subclinical hypothyroidism may help identify pregnant women at high risk for SGA.