Neonatal mortality risk for vulnerable newborn types in 15 countries using 125.5 million nationwide birth outcome records, 2000–2020

Abstract

ObjectiveTo compare neonatal mortality associated with six novel vulnerable newborn types in 125.5 million live births across 15 countries, 2000–2020.DesignPopulation‐based, multi‐country study.SettingNational data systems in 15 middle‐ and high‐income countries.MethodsWe used individual‐level data sets identified for the Vulnerable Newborn Measurement Collaboration. We examined the contribution to neonatal mortality of six newborn types combining gestational age (preterm [PT] versus term [T]) and size‐for‐gestational age (small [SGA], <10th centile, appropriate [AGA], 10th–90th centile or large [LGA], >90th centile) according to INTERGROWTH‐21st newborn standards. Newborn babies with PT or SGA were defined as small and T + LGA was considered as large. We calculated risk ratios (RRs) and population attributable risks (PAR%) for the six newborn types.Main outcome measuresMortality of six newborn types.ResultsOf 125.5 million live births analysed, risk ratios were highest among PT + SGA (median 67.2, interquartile range [IQR] 45.6–73.9), PT + AGA (median 34.3, IQR 23.9–37.5) and PT + LGA (median 28.3, IQR 18.4–32.3). At the population level, PT + AGA was the greatest contributor to newborn mortality (median PAR% 53.7, IQR 44.5–54.9). Mortality risk was highest among newborns born before 28 weeks (median RR 279.5, IQR 234.2–388.5) compared with babies born between 37 and 42 completed weeks or with a birthweight less than 1000 g (median RR 282.8, IQR 194.7–342.8) compared with those between 2500 g and 4000 g as a reference group.ConclusionPreterm newborn types were the most vulnerable, and associated with the highest mortality, particularly with co‐existence of preterm and SGA. As PT + AGA is more prevalent, it is responsible for the greatest burden of neonatal deaths at population level.

Small babies, big risks: global estimates of prevalence and mortality for vulnerable newborns to accelerate change and improve counting

“…The types have been simplified by focusing on three SVN types in this paper, noting that 99.5% of LBW newborns are in the three categories of PT, SGA or PT+SGA. It is justifiable to combine preterm AGA and preterm LGA since the mortality risks are very similar (web annex III figure E1, E2) (64). Since short length of gestation is the strongest predictor of mortality risk and longer term adverse neurodevelopmental outcomes, (45,65), splitting the preterm categories into subgroups based on maturity could provide useful additional information for both policy and programming and individual care.…”

“…Further categorisations of severity of SGA e.g., <3 rd centile could be informative (66). Whilst the smallest newborns have the highest mortality risk, large for gestational age (LGA) is increasing in prevalence and may in some settings be associated with an increase in risk; it could also be included to provide a more complete overview (64). More work is still needed to better understand and link these types, including LGA, to life-course outcomes.…”