Abstract
Intra-amniotic thyroxine (200–500 ug) was administered weekly to 29 women in the third trimester to enhance fetal maturation. Lecithin-sphingomyelin ratio (L/S) and epidermal growth factor (EGF) were measured in amniotic fluid (AF) before (n = 58) and after (n = 92) administration of thyroxine. The AF L/S ratio and EGF concentration increased linearly with increasing gestational age both before (r = 0.76, p > 0.0001; r = 0.41, p > 0.001, respectively) and after (r = 0.62, p > 0.0001; r = 0.43, p > 0.001 respectively) initiation of thyroxine treatment. The slopes of gestational age vs L/S (0.07) and EGF (0.004) before T4 increased significantly after initiation of T4 therapy (L/S:0.23, p > 0.001; EGF:0.015, p > 0.01, respectively). L/S ratios correlated with AF EGF levels before (r = 0.77, p > 0.001) and after (r = 0.63, p > 0.001) initiation of T4 therapy. These results demonstrate that intra-amniotic thyroxine accelerates not only the progression of the amniotic fluid L/S ratio, but the appearance of EGF.