Neonatal mortality in small for gestational age infants based on reference local newborn curve at secondary and tertiary hospitals in Indonesia

Background: Small for gestational (SGA) infants during the neonatal period have risks of mortality and sequelae for survival. Two - third of neonatal mortality occurs in the first weeks of life. Prevalence of SGA depends on the newbon curve used. Objectives of the study were to know the conditions that posed the risk of early neonatal and neonatal mortality, to identify preterm/full-term and SGA/appropriate gestational age (AGA) infants with cumulative mortality incident (CMI), to compare 5- year-period of early and neonatal mortality, and to investigate CMI on neonatal mortality of four categories during 5-year-period. Methods: A retrospective cohort study on all live births, during 1998–2017, was conducted in Sleman and Sardjito hospitals, Yogyakarta, Indonesia. Based on the reference local curve, the eligible subjects were categorized into SGA and AGA infants. The analyses were based on preterm/full-term and SGA/AGA, thus resulting in 4 categories: preterm-SGA, preterm-AGA, full-term-SGA and full-term-AGA. Analysis was made with Unadjusted Hazard Ratio (HR) by Simple Cox Regression and Adjusted HR was calculated by Multiple Cox Regression, survival analysis to calculate CMI, and analysis mortality for 5-year period (1998–2002, 2003–2007, 2008–2012, 2013–2017). Result: There were 35,649 live births eligible for the study. Respiratory distress was the highest risk with HR 9,46, followed by asphyxia with HR 5,08, mother’s death with HR 227, extra-health facility with HR 1,97, symmetrical SGA with HR 1,97, preterm-AGA with HR 1,75, low birth weight (LBW) with HR 1,64, primary health facility with HR 1,33, and boys with HR 1,16 consecutively. Early neonatal mortality in 4 categories by survival analysis revealed the highest CMI in preterm SGA. Similar result was found in neonatal mortality. Analysis of 5-year period unveiled the highest CMI during 1998–2002. The highest CMI based on the four categories, however, was found in preterm-SGA. Conclusion: Respiratory distress posed the highest HR in early and neonatal mortality. Survival analysis showing the highest CMI on early and neonatal mortality was identified in preterm-SGA. The 5 - year - period of neonatal mortality showed the highest CMI during 1998–2002 period, whereas based on 4 SGA categories, preterm-SGA demonstrated the highest CMI. © 2023, The Author(s).