Stillbirth rate trends across 25 European countries between 2010 and 2021: the contribution of maternal age and multiplicity

Abstract

Stillbirth rates have stalled or increased in some European countries during the last decade. We investigate to what extent time-trends and between-country differences in stillbirth rates are explained by the changing prevalence of advanced maternal age and teenage pregnancies or multiple births. We analysed data on stillbirths and live births by maternal age and multiplicity from 2010 to 2021 in 25 European countries using Kitagawa decomposition to separate rate differences into compositional and rate components. Rates significantly decreased in six countries, but increased in two. Changes in maternal age structure reduced national stillbirth rates by a maximum of 0.04 per 1000 in the Netherlands and increased rates by up to 0.85 in Cyprus. Changes in the prevalence of multiple births decreased rates by up to 0.19 in the Netherlands and increased rates by up to 0.01 across multiple countries. Maternal age differences explained between 0.11 of the below-European average stillbirth rate in Belgium and 0.13 of the above-average rate in Ireland. Excluding Cyprus, differences in multiple births explained between 0.05 of the below-average rate in Malta and 0.03 of the above-average rate in Ireland. For most countries, the increase in advanced-age pregnancies contributed to rising stillbirth rates over time, while reductions in multiples led to decreases in rates. However, large parts of the trends remain unexplained by those factors. By 2021, neither factor explained the differences between countries, due to increased compositional uniformity and declining stillbirth risk for advanced maternal age.

Figure 1.

Trends in stillbirth rates between 2010 and 2021 across 25 European countries. The dots mark the annual rates (2013–2021 for the UK and Slovenia, 2014–2021 for France, and 2015–2021 for Luxembourg). Slope estimates of the trend in stillbirth rates originate either from a simple linear regression (orange) or, if a significant breakpoint was identified, from a segmented regression (green). Mean predictions and 95% confidence intervals from the regression fit are superimposed. MK test for monotonic trend with correction for autocorrelation. *P < .05, **P < .01, ***P < .001. Source: Euro-Peristat Network.

Figure 2.

Change in the composition of births across 24 European countries between 2010 and 2021. (A) Maternal age structure from 2010 to 2021. (B) Births from multiple pregnancies per 100 total births from 2010 to 2021. Source: Euro-Peristat Network.

Figure 3.

Decomposition of the difference in stillbirth rates by country between 2010 and 2021 into the component of changing stillbirth rates (grey), changing maternal age composition (red), and changing prevalence of multiples (blue). Decomposition of maternal age structure and multiples were performed separately. The black dot represents the rate in 2010 [2015 for the UK, France, and Slovenia (age and multiples) and Spain (multiples)] and the end of the arrow represents the rate in 2021. Source: Euro-Peristat Network.

Figure 4.

Decomposition of the difference in stillbirth rates between countries and European average in 2021 into the component of changing stillbirth rates (grey), changing maternal age composition (red), and changing prevalence of multiples (blue). Decomposition of maternal age structure and multiples were performed separately. The black dot represents the average rate in 2021 across all countries, and the end of the arrow represents the national rate in 2021. Source: Euro-Peristat Network.