Gonzalez et al found synergistic effects of T3 and dexamethasone measured in human fetal lung in organ culture, and suggested that T3 and dexamethasone act at different biochemical sites. Animal and human studies related to combined hormonal therapy will be reviewed later. All of the conditions that predispose patients to preterm labor and delivery have been considered as indication for T4 treatment. Our most frequent condition is arrested preterm labor. In our series, perhaps the most notable benefits derived from acceleration of fetal maturation were obtained in cases of maternal malignancy, which permitted earlier initiation of chemotherapy and radiotherapy.
Similar considerations apply to patients with maternal sickle cell disease.
By initiating acceleration of fetal maturation at 31 weeks, and delivering at 34 to 35 weeks, one may eliminate the problems created by macrosomia, and at the same time ensure that the newborn will be cared for in the regular nursery. Preeclampsia is among the most controversial indication for T4 therapy. Prolongation of gestation is very limited in some cases. Our protocol for administration of T4 consists of sonographic evaluation of the fetus to rule out fetal structural anomalies and to confirm gestational age. Under sonographic guidance, amniocentesis is performed using a 22-gauge spinal needle.