Prevalence estimates of small vulnerable newborns in China (2012-22): a modelling study

Persistent efforts are imperative to improve neonatal health outcomes, especially considering China's evolving fertility policies and persistent regional health disparities. The Small Vulnerable Newborn Consortium has proposed a framework combining preterm birth (<37 weeks of gestation), small for gestational age (SGA) by the INTERGROWTH-21st standard, and low birthweight (LBW; <2500 g) under the category of small vulnerable newborns (SVNs); however, updated, reliable data on SVNs from mainland China are scarce. To improve children's health in China and identify a strategic entry point to help narrow regional disparities, we estimated the prevalence of SVNs and four SVN subtypes at the national and provincial levels.

We used data from China's National Maternal Near Miss Surveillance System (NMNMSS) for pregnant women discharged from Jan 1, 2012, to Dec 31, 2022, at 441 hospitals located in 30 mainland provinces (excluding Tibet) to estimate the prevalence of SVNs and the four mutually exclusive SVN types (preterm SGA; preterm non-SGA; term [≥37 weeks' gestation] SGA; and term non-SGA but LBW [LBW only]) at the national and provincial levels. Provincial data were aggregated by applying age-specific weights determined by comparing the maternal age-specific livebirth distributions in a given province and year between the NMNMSS and the Global Burden of Disease Study 2019 datasets. Bayesian multilevel mixed-effects linear regression was used to estimate the median prevalence ratios (PRs) and their corresponding 95% uncertainty intervals (UIs). The average annual percent change (AAPC) with 95% CI was calculated by assuming a Poisson distribution with the year as the predictor variable.

We estimated the annual PRs of SVNs and the four SVN subtypes using data from 14 221 823 livebirths recorded by the NMNMSS between 2012 and 2022. In 2022, an estimated 13·2 per 100 liveborn newborns (95% UI 12·5 to 14·0) in mainland China were identified as SVNs, which predominantly comprised infants who were born preterm non-SGA, followed by term SGA, preterm SGA, and LBW only. The national PR of SVNs remained stable overall from 2012 to 2022 (AAPC -0·4%, 95% CI -0·9 to 0·04), although an initial decrease was followed by an increase after 2018. The PR of term SGA livebirths decreased from 7·1 per 100 livebirths (95% UI 6·6 to 7·5) in 2012 to 5·2 per 100 livebirths (95% UI 4·9 to 5·6) in 2022 (AAPC -2·9%, 95% CI -3·6 to -2·2), whereas the PRs of preterm non-SGA livebirths and LBW-only livebirths increased over the same period (preterm non-SGA 6·0 per 100 livebirths [95% UI 5·7 to 6·3] in 2012 vs 7·0 per 100 livebirths [95% UI 6·7 to 7·4] in 2022, AAPC 1·8% [95% CI 1·5 to 2·1]; LBW only 0·1 per 100 livebirths [95% UI 0·1 to 0·1] in 2012 vs 0·2 per 100 livebirths [95% UI 0·2 to 0·2] in 2022, AAPC 5·4% [95% CI 4·7 to 6·1]). In 2022, the highest PRs of SVN, preterm SGA, and term SGA livebirths were observed in Qinghai, whereas Liaoning had the highest PR of preterm non-SGA livebirths and Chongqing had the highest PR of LBW-only livebirths. Between 2012 and 2022, the PR of SVNs increased in Heilongjiang, Beijing, Hebei, Inner Mongolia, Jiangsu, Shanghai, and Xinjiang, with Heilongjiang showing the most rapid increase (AAPC 2·0%, 95% CI 1·6-2·5). The PR of preterm SGA livebirths increased the most in Inner Mongolia, Gansu, Hebei, Qinghai, and Shanghai, whereas the prevalence of preterm non-SGA livebirths increased the most in Inner Mongolia, Heilongjiang, Ningxia, Xinjiang, and Jiangsu.

Although the prevalence of SVNs in mainland China has stabilised overall, a reversal occurred after 2018, with western provinces showing substantially higher levels than central and eastern provinces. Reducing the burden of SVN in China requires particular attention to preterm-onset SVN. Continued attention on SVNs can help narrow regional disparities in child health, and thereby advance the target of Sustainable Development Goal 3.2 to end preventable deaths among neonates and children under 5 years old by 2030.

National Key Research and Development Program of China.