Medicaid Eligibility, Prenatal Care, and the Outcome of Pregnancy

To the Editor. —  The study by Piper et al¹ was interesting and timely. The authors provide data to suggest that providing eligibility for public insurance is not sufficient to affect health. I agree with the sentiments of Guyer's editorial² that the maternity care system itself must be addressed, not only insurance coverage.Still, I would like to make two points. First, the abstract by Piper et al states that "there were no concomitant improvements in... neonatal mortality." The data presented show a reduction in mortality from 5.6 per 1000 to 5.1 per 1000, an 8.9% reduction. Certainly this reduction could have been due to chance; the statistical analysis of the data does not allow one to conclude with 95% certainty that the difference was not due to chance. However, the observed improvement in neonatal mortality was significant to the 90% level of confidence, and so statistical analysis