highly significantP < 0.001
After adjusting for several maternal and pregnancy factors including maternal age, smoking habits, and infant weight at birth, the relationship between TPO status and infant head circumference at birth was not significant in the overall population but was highly significant among infants born to white non-Hispanic mothers ( β = −0.727; standard error (SE) = 0.214; P < 0.001) and among those in the “other” racial/ethnic group ( β = −1.636; SE = 0.713; P < 0.05), distinguishing race/ethnicity as an effect modifier in the relationship between maternal TPO status and fetal brain growth.