Changes in the Prevalence of Maternal Chronic Conditions During Pregnancy: A Nationwide Age-Period-Cohort Analysis

( BJOG . 2025;132:44-52. doi: 10.1111/1471-0528.17885) The prevalence of chronic conditions throughout the world has been rising, and this is consistent both across countries and across age groups. In those of childbearing age, it is one of the driving causes of maternal mortality and severe maternal morbidity and represents a significant challenge for nearly 1 in 10 pregnancies. The reasons for this rise in chronic conditions are unclear, though some explanations could include the shift toward childbearing at more advanced ages in high-income countries. Other explanations could include rising rates of obesity and births to undocumented immigrants or asylum seekers in high-income countries. Currently, there are few studies that evaluate the prevalence or consequences of pre-existing chronic conditions in pregnancy; this study aims to address this gap by evaluating the trend of preexisting conditions with respect to age, time period, and birth cohort effects in Sweden, as well as assessing changes in obesity and immigration in the context of these trends.