Long-term trends in the global burden of maternal abortion and miscarriage from 1990 to 2021: joinpoint regression and age-period-cohort analysis.

Background: Maternal abortion and miscarriage are significant contributors to the global burden of maternal health conditions. Iron deficiency remains a critical risk factor, significantly impacting reproductive health outcomes, particularly in low socio-demographic index (SDI) regions. This study aims to assess long-term trends in the incidence, mortality, and disability-adjusted life years (DALYs) of maternal abortion and miscarriage from 1990 to 2021 using the Global Burden of Disease (GBD) 2021. Additionally, we evaluate the role of iron deficiency as a risk factor and project future burden estimates up to 2051.

Methods: Utilizing the GBD 2021 dataset across 204 countries and territories, the study retrospectively analyzed long-term trends in maternal abortion and miscarriage from 1990 to 2021. Joinpoint regression was applied to identify temporal trends in age-standardized incidence rate (ASIR), age-standardized mortality rate (ASMR), and age-standardized DALYs rate (ASDR). An age-period-cohort (APC) model was used to assess the independent effects of age, period, and cohort, while future projections were generated using Bayesian age-period-cohort (BAPC) modeling.

Results: In 2021, the global ASIR of maternal abortion and miscarriage was 1001.64 per 100,000 population (95% UI: 775.97-1261.67), with the highest burden in low SDI regions (ASIR = 1715.1 per 100,000 population). The ASMR, reflecting maternal mortality due to abortion and miscarriage, was 0.42 per 100,000 population (95% UI: 0.36-0.52). The ASDR, capturing the total burden including both premature mortality and disability, was 25.73 per 100,000 population (95% UI: 21.82-31.02). The global ASIR declined at an annual percentage change (APC) of -2.32% from 1990 to 1994 and by -2.00% from 2015 to 2019.

Conclusions: The global burden of maternal abortion and miscarriage has decreased, with iron deficiency remaining a critical risk factor in low SDI regions, particularly among women aged 20-34. Projections suggest declines in ASIR over the next 30 years.