Temporal Trend and Risk Factors for Respiratory Distress Syndrome-Associated Neonatal Mortality in Preterm Infants: A Population-Based Study in a Middle-Income Country.

OBJECTIVE

This article aimed to report a temporal series of respiratory distress syndrome (RDS)-associated neonatal mortality rates in preterm live births in São Paulo state, Brazil, and to identify social, maternal, and neonatal characteristics associated with these deaths.

STUDY DESIGN

This is a population-based study of all live births with gestational age (GA) between 22 and 36 weeks, birth weight ≥400 g, without congenital anomalies from mothers living in São Paulo state during 2004 to 2015. RDS-associated neonatal mortality was defined as death up to 27 days after birth with ICD-10 codes P22.0 or P28.0. RDS-associated neonatal mortality rate (annual percent change [APC] with 95% confidence intervals [95% CIs]) was analyzed by Prais-Winsten. Kaplan-Meier estimator identified the time after birth that the RDS-associated neonatal death occurred. Poisson's regression model compared social maternal and neonatal characteristics between preterm live births that survived the neonatal period and those with RDS-associated neonatal deaths, with results expressed in incidence rate ratio and 95% CI.

RESULTS

A total of 645,276 preterm live births were included in the study, of which 612,110 survived and 11,078 had RDS-associated neonatal deaths. RDS-associated neonatal mortality rate was 17.17 per thousand preterm live births, with a decreasing annual trend (APC: -6.50%; 95% CI: -9.11 to -3.82%). The median time of these deaths was 48 hours after birth. The following risk factors for RDS-associated neonatal death were identified: maternal schooling ≤7 years (1.18; 1.09-1.29), zero to three prenatal care visits (1.25; 1.18-1.32), multiple pregnancy (1.24; 1.16-1.33), vaginal delivery (1.29; 1.22-1.36), GA 22 to 27 weeks (106.35; 98.36-114.98), GA 28 to 31 weeks (20.12; 18.62-21.73), male sex (1.16; 1.10-1.22), and 5-minute Apgar scores of 0 to 3 (6.74; 6.08-7.47) and 4 to 6 (3.97; 3.72-4.23).

CONCLUSION

During the study period, RDS-associated neonatal mortality rates showed significant reduction. The relationship between RDS-associated neonatal deaths and social, maternal, and neonatal factors suggests the need for perinatal strategies to reduce prematurity and to improve the initial management of preterm infants.

KEY POINTS

· RDS is associated with preterm live births.. · Impact of RDS-associated neonatal mortality in middle-income countries is scarce.. · Qualified perinatal care can reduce RDS-associated neonatal mortality..