Thyroid hormone concentrations in preterm infants born to pre-eclamptic women with placental insufficiency

The aim of this study was to compare thyroid function in preterm infants born to women with placental insufficiency (n = 15) and those born to women without placental insufficiency (n = 13). Gestational ages ranged between 28 and 33 weeks. Concentrations of free thyroxine (FT4), thyrotropin (TSH), triiodothyronine (T3) and reverse T3 (rT3) were measured by radioimmmunoassays in cord blood and on d 1, 3, 5, 7, 14 and 21. Infants born to the women with placental insufficiency had significantly lower mean FT4 (p = 0.001), TSH (p = 0.002) and rT3 values (p = 0.025) in cord blood, and higher rT3 values on d 5 (p = 0.019) and d 7 (p = 0.025). The following conclusions were reached: (i) preterm infants born to pre-eclamptic women with placental insufficiency have intact hypothalamic-pituitary-thyroid axes; (ii) compared to preterm infants born to healthy women, preterm infants born to pre-eclamptic women with placental insufficiency have lower FT4 and TSH concentrations before birth and (iii) elevated rT3 concentrations after birth, suggesting a temporarily impaired hepatic type 1 deiodination process.