Birth weight and age-specific analysis of the 1990 US infant mortality drop. Was it surfactant?
The hypothesis that surfactant was partially responsible for the overall infant mortality drop in 1990 is supported by the lower than expected mortality among infants weighing 750 to 1749 g. However, the unexpected improvement in postneonatal mortality among infants weighing 2500 g or more was responsible for a substantial portion of the overall decline and suggests that other factors also acted to decrease US infant mortality in 1990.
No evidence for tachyphylaxis in SD/D treatment by PTZ-based shampoos was found. Compliance could explain the decreasing response rate seen over time; the solution is to choose an affordable therapeutic product that is effective long term without cosmetic trade-offs.