Secular Trends in Preterm Birth Rates: Uncovering the Primary Challenge for Perinatal Medicine in Greece

Preterm labour is a serious pregnancy complication that is the primary cause of infant mortality, with detrimental impacts on the offspring and the mother in the short as well as the long term. This study aims to comprehensively present the time trends of national preterm birth rates (PBRs) in Greece.

Official national data regarding live births in Greece were acquired from the Hellenic Statistical Authority, and the annual total PBR and rates for gestational age groups were computed per 100 total live births spanning from 1980 to 2022. Time trends were analyzed through joinpoint regression analysis, and annual percent changes (APC) and average annual percent change (AAPC) were calculated with a 95% confidence interval (95% CI).

Following a steady decline from 4.66% in 1980 to a historic low of 2.77% in 1991 with an APC of -5.1 (-6.2 to -4.2), the PBR exhibited a dramatic increase during 1991-2011 with an APC of 7.3 (6.9 to 7.8). Subsequently, between 2011 and 2022, the rise in PBR was attenuated, showing a slight statistically non-significant upward trend (APC = 0.5, 95% CI: -0.6 to 1.5). This led to a historical high of 12.07% in 2018, 4.4 times higher than that in 1991, and eventually, the PBR reached 11.90% in 2022. From 1991 to 2022, there were sharper increases in the rates of moderate (32-33 weeks) and late (34-36 weeks) preterm births, with AAPCs of 4.9 (3.5-6.4) and 5.8 (5.3-6.3), respectively. In contrast, the rates of extremely (<28 weeks) and very (28-31 weeks) preterm births saw slower growth, with AAPCs of 2.2 (1.7-2.7) and 0.7 (0.5-1.0), respectively.

The PBR in Greece more than quadrupled during 1991-2022, mainly due to increases in moderate and late preterm births. Although its rise has markedly decelerated since 2011, amidst the country's economic recession, the PBR is alarmingly higher than those in all other European and developed nations. More than one in nine neonates is born prematurely in the Greek population, posing challenges in implementing evidence-based prevention strategies and perinatal care.