Mortality in Multiple versus Singleton Very Low Birth Weight Infants in Germany: A Population-Based Study.

INTRODUCTION

In several large cohorts from the USA and China, multiple as opposed to singleton birth was found to be associated with increased mortality, while studies from European countries have yielded conflicting results. We aimed to assess the association between plurality and survival of very low birth weight infants in relation to gestational age.

METHODS

Data of preterm infants <1,500 g birth weight obtained from annually published quality improvement data mandatorily collected from all hospitals in Germany (2010-2017, 2019-2024) were analyzed for mortality of singletons versus multiples.

RESULTS

Among infants below 1,500 g birth weight (n = 128,057), twins and higher-order multiples accounted for 28.2% and 3.9%, as opposed to 3.5% and 0.1% in all neonates (n = 9,986,821). Mortality prior to discharge was lower in twins (7.3%) and triplets (6.2%) than in singletons (9.0%) (relative risk [RR] 0.811, 95% confidence interval [CI] 0.777-0.846, and 0.689 [0.618-0.769], respectively). However, in infants below 25 weeks' gestation, mortality was higher in multiples (40.5%) than in singletons (37.6%) (RR [95% CI] 1.076 [1.031-1.124]), whereas it was lower in multiples than in singleton infants with a gestational age of 25-27 weeks (8.5% vs. 9.4%, RR [95% CI] 0.907 [0.837-0.983]), 28-30 weeks (2.1% vs. 2.9%, RR [95% CI] 0.737 [0.650-0.835]), and more than 30 weeks (1.2% vs. 2.0%, RR [95% CI] 0.583 [0.484-0.703]).

CONCLUSIONS

In this large population-based cohort of preterm infants below 1,500 g birth weight, multiples had higher survival rates than singletons, except those born before 25 weeks' gestation.