Neonatal mortality risk of large-for-gestational-age and macrosomic live births in 15 countries, including 115.6 million nationwide linked records, 2000–2020

Abstract

Objective

We aimed to compare the prevalence and neonatal mortality associated with large for gestational age (LGA) and macrosomia among 115.6 million live births in 15 countries, between 2000 and 2020.

Design

Population-based, multi-country study.

Setting

National healthcare systems.

Population

Liveborn infants.

Methods

We used individual-level data identified for the Vulnerable Newborn Measurement Collaboration. We calculated the prevalence and relative risk (RR) of neonatal mortality among live births born at term + LGA (>90th centile, and also >95th and >97th centiles when the data were available) versus term + appropriate for gestational age (AGA, 10th–90th centiles) and macrosomic (≥4000, ≥4500 and ≥5000 g, regardless of gestational age) versus 2500–3999 g. INTERGROWTH 21st served as the reference population.

Main outcome measures

Prevalence and neonatal mortality risks.

Results

Large for gestational age was common (median prevalence 18.2%; interquartile range, IQR, 13.5%–22.0%), and overall was associated with a lower neonatal mortality risk compared with AGA (RR 0.83, 95% CI 0.77–0.89). Around one in ten babies were ≥4000 g (median prevalence 9.6% (IQR 6.4%–13.3%), with 1.2% (IQR 0.7%–2.0%) ≥4500 g and with 0.2% (IQR 0.1%–0.2%) ≥5000 g). Overall, macrosomia of ≥4000 g was not associated with increased neonatal mortality risk (RR 0.80, 95% CI 0.69–0.94); however, a higher risk was observed for birthweights of ≥4500 g (RR 1.52, 95% CI 1.10–2.11) and ≥5000 g (RR 4.54, 95% CI 2.58–7.99), compared with birthweights of 2500–3999 g, with the highest risk observed in the first 7 days of life.

Conclusions

In this population, birthweight of ≥4500 g was the most useful marker for early mortality risk in big babies and could be used to guide clinical management decisions.