# Temporal Trends in the Impact of Preterm Birth on Low Birthweight Rates in Greece

## TL;DR

This study shows that preterm births are the main cause of rising low birthweight rates in Greece over the past three decades.

## Contribution

The study quantifies how increases in preterm births have driven the rise in low birthweight rates in Greece.

## Key findings

- Preterm birth rates and low birthweight rates in Greece have risen sharply and are strongly correlated.
- The population risk of low birthweight due to prematurity increased from 25.8% in 1991 to 68.2% in 2021.
- The entire increase in low birthweight rates between 1991 and 2023 was fully explained by the rise in preterm births.

## Abstract

Background and objectives: In Greece, both the preterm birth rate (PBR) and the low birthweight rate (LBWR) have risen sharply in recent decades, reaching among the highest levels in high-income countries and posing a substantial public health concern. This study aimed to quantify the contribution of preterm births to the national LBW burden and to determine the extent to which the rise in PBR has driven the increase in LBWR.

Methods: The analysis included 4,585,090 live births recorded in Greece from 1980 to 2023, stratified by gestational age and birthweight. Temporal trends were assessed using joinpoint regression analysis. For each segment between two joinpoints, the annual percent change (APC) was calculated with 95% confidence intervals (CIs), and statistical significance was set at p < 0.05.

Results: From 1980 to 2023, both LBWR and PBR increased substantially and were strongly correlated (rho = 0.858, 95% CI: 0.725-0.929, p < 0.001). The preterm LBWR remained stable from 1987 to 2004, then rose significantly thereafter (APC = 0.5, 95% CI: 0.2-0.9, p = 0.027). In contrast, the term LBWR increased during the 1980s and 1990s, declined significantly from 2002 to 2017 (APC = -3.5, 95% CI: -6.2 to -2.7, p = 0.033), and then stabilized. The population attributable risk (PAR, %) of LBW due to prematurity increased from a low of 25.8% in 1991 to a historic peak of 68.2% in 2021 (67.1% in 2023), with statistically significant rises during 1991-2004 (APC = 2.5, 95% CI: 1.3-7.7, p = 0.024), 2004-2009 (APC = 9.1, 95% CI: 2.4-13.9, p = 0.021), and 2009-2023 (APC = 1.4, 95% CI: 0.7-2.0, p = 0.014). The proportion of LBW neonates born preterm rose from a minimum of 27.8% in 1991 to a peak of 72.0% in 2021 (71.2% in 2023). The entire increase in LBWR between 1991 and 2023 was fully explained by the concurrent rise in PBR.

Conclusions: This nationwide study demonstrates that preterm birth is the principal driver of Greece’s high LBWR. The population risk of LBW attributable to prematurity has increased markedly over the past three decades, and the sustained rise in LBWR is entirely accounted for by the parallel increase in PBR. These findings underscore the urgent need for targeted, evidence-based clinical and public health strategies to reduce prematurity and improve perinatal outcomes.