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Mortality in Multiple versus Singleton Very Low Birth Weight Infants in Germany: A Population-Based Study
Fabienne Kühne1, Vinzenz Boos2, Christoph Bührer3
1Department of Neonatology, Charité-Universitätsmedizin Berlin, Berlin, Germany, fabienne.kuehne@charite.de.
Insights
Multiple births in very low birth weight infants show higher survival rates than singletons, except for extremely preterm infants born before 25 weeks gestation. This finding impacts neonatal care strategies for high-risk pregnancies.
Area of Science:
- Neonatalogy
- Perinatology
- Public Health
Background:
- Conflicting international data exist on mortality rates for multiple births versus singleton births.
- Previous studies suggest multiple births are associated with increased mortality, but European data are inconsistent.
- Gestational age is a critical factor in preterm infant survival.
Purpose of the Study:
- To investigate the association between birth plurality and survival rates in very low birth weight infants.
- To analyze survival differences between singletons and multiples in relation to gestational age.
- To provide evidence for optimizing care for preterm infants.
Main Methods:
- Analysis of a large German population-based cohort of preterm infants (<1500g birth weight) from 2010-2017 and 2019-2024.
- Mandatory quality improvement data from all German hospitals were used.
- Comparison of mortality rates between singleton and multiple births, stratified by gestational age.
Main Results:
- Multiples constituted a significant proportion (28.2% twins, 3.9% triplets) of infants <1500g birth weight.
- Overall mortality was lower for twins (7.3%) and triplets (6.2%) compared to singletons (9.0%).
- However, infants born before 25 weeks gestation had higher mortality if they were multiples (40.5%) versus singletons (37.6%). Survival improved for multiples in later gestational age groups (25-27, 28-30, >30 weeks).
Conclusions:
- In very low birth weight infants, multiple births are associated with higher survival rates than singletons.
- This survival advantage for multiples is not observed in extremely preterm infants born before 25 weeks gestation.
- Gestational age is a crucial determinant of survival differences between singleton and multiple births in the neonatal period.
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.
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