OBJECTIVEWe evaluated the effect of the Newborns' and Mothers' Health Protection Act on clinical and cost outcomes.METHODSWe conducted an observational study of 18,023 healthy, mother-infant dyads before (n= 8670) and after (n= 9353) implementation of the Newborns' and Mothers' Health Protection Act legislation. Logistic regression was used to calculate adjusted odds ratios (ORs) for the following outcome measures: length of stay at least 48 hours, satisfaction with maternal length of stay, 7- and 30-day hospital readmission utilization, and 7- and 30-day emergency room utilization. Analysis of covariance was used to evaluate adjusted mean hospitalization costs per delivery.RESULTSMothers in the postlegislation period were more likely to have hospital stays at least 48 hours (OR 3.99; 95% confidence interval [CI] 3.57, 4.44) and rate their length of stay as “about right” (OR 5.54; 95% CI 4.76, 6.46) compared with mothers in the prelegislation period. Neonates in the postlegislation period were more likely to have hospital stays of at least 48 hours (OR 3.96; 95% CI 3.54, 4.43) and less likely to be rehospitalized within 7 days after hospitalization (OR 0.61; 95% CI 0.40, 0.95) compared with neonates in the prelegislation period. Adjusted mean hospitalization costs increased $116 per delivery in the postlegislation period.CONCLUSIONSAfter implementation of the Newborns' and Mothers' Health Protection Act legislation, maternal and newborn length of stay and maternal satisfaction with length of stay increased substantially, and hospitalization costs increased significantly. The strongest clinical benefit was observed among neonates who were at a lower risk for hospitalization within 1 week of discharge. With the exception of 30-day emergency room utilization, there was insufficient statistical power to test for differences among other maternal clinical outcomes.