Cognitive evaluation using the Infants Bailey Scales and the Stanford Binet intelligence Scale was performed for 35 treated infants and for 40 infants in the matched group. Reduction in the relative frequency of RDS, and in the need to care for the prematurely born infant in the intensive care unit, is only part of the potential benefits of this treatment. Preliminary evidence is accumulating that prenatal treatment with T4 may also reduce the relative frequency and the extent of permanent disabilities, such as ROP, BPD and neurological abnormalities. Because the treatment can be done on an outpatient basis, the cost is modest. The need of amniocentesis is a drawback, but because the procedure carries a low risk when performed under ultrasound guidance, and because it is often required for the assessment of fetal maturity, the benefit to risk ratio is high.
Much work still remains to be done.
The use of injectable T3 could decrease the time required for the treatment to be effective. The dose interval of T4 treatment should be addressed. The additive of potentiating effects of other hormones, particularly steroids, should be evaluated. Finally, the effects on the rate of maturation of other systems such as the fetal immune system merit attention.