Vulnerable newborn types: Analysis of population-based registries for 165 million births in 23 countries, 2000-2021

Abstract

Objective: To examine the prevalence of novel newborn types among 165 million live births in 23 countries from 2000 to 2021.

Design: Population-based, multi-country analysis.

Setting: National data systems in 23 middle- and high-income countries.

Population: Liveborn infants.

Methods: Country teams with high-quality data were invited to be part of the Vulnerable Newborn Measurement Collaboration. We classified live births by six newborn types based on gestational age information (preterm <37 weeks versus term ≥37 weeks) and size for gestational age defined as small (SGA, <10th centile), appropriate (10th-90th centiles), or large (LGA, >90th centile) for gestational age, according to INTERGROWTH-21st standards. We considered small newborn types of any combination of preterm or SGA, and term + LGA was considered large. Time trends were analysed using 3-year moving averages for small and large types.

Main outcome measures: Prevalence of six newborn types.

Results: We analysed 165 017 419 live births and the median prevalence of small types was 11.7% - highest in Malaysia (26%) and Qatar (15.7%). Overall, 18.1% of newborns were large (term + LGA) and was highest in Estonia 28.8% and Denmark 25.9%. Time trends of small and large infants were relatively stable in most countries.

Conclusions: The distribution of newborn types varies across the 23 middle- and high-income countries. Small newborn types were highest in west Asian countries and large types were highest in Europe. To better understand the global patterns of these novel newborn types, more information is needed, especially from low- and middle-income countries.

Keywords: low birthweight; newborn; preterm birth; size for gestational age.

FIGURE 1

Overview of vulnerable newborn types based on gestational age, size for gestational age and birthweight. This figure illustrates the six newborn types (A) used in the main analysis and more granular expansion of these types adding the birthweight dimension (B) used in the secondary analysis in this paper. Original newborn types proposed by Ashorn et al. are shown as Appendix S4b.

FIGURE 2

Input data set for Vulnerable Newborn national prevalence. (A) Flow chart for data inclusions and exclusions. ^aFocus of searches for subnational data see ref. for further details. ^bDefined as having input data meeting high‐quality criteria for previous UN preterm birth, and low birthweight estimates, or the country having a strong national health system defined as at least 80% facility births. (B) Distribution of 165 million live births included from national data sets in 23 countries, by Sustainable Development Goal (SDG) Region.

FIGURE 3

Median and interquartile range of national prevalence of six newborn types among 165 017 419 live births included from 23 countries. National data are presented as separate analyses as provided by devolved nations (England & Wales, Northern Ireland, Scotland) from the United Kingdom.

FIGURE 4

Prevalence of six newborn types among 165 017 419 live births included from 23 countries, by country and Sustainable Development Goal Region. National data are presented as separate data as provided by devolved nations (England & Wales, Northern Ireland, Scotland) from the United Kingdom.

FIGURE 5

Rolling average of the percentage of live births of different newborn types in 20 countries. Excluding Argentina, the Czech Republic and Northern Ireland for providing pooled data or less than three disaggregated years. Small vulnerable newborns include: PT + SGA, PT + AGA, PT + LGA, T + SGA. Coloured lines are Loess smoothers, grey shading shows the confidence intervals.