Secular Trends in Stillbirth by Maternal Socioeconomic Status in Spain 2007-2015: A Population-Based Study of 4 million births

Background: Stillbirth, one of the urgent concerns of preventable perinatal deaths, has wide-reaching consequences for society. We studied secular stillbirth trends by maternal socioeconomic status (SES) in Spain. Methods: We developed a population-based observational study, including 4,083,919 births during 2007-2015. We estimate stillbirth rates and secular trends by maternal SES, using the fetuses-at-risk approach. We also evaluated the joint effect of maternal educational attainment and the Human Development Index (HDI) of women's country of origin on the risk of stillbirth. Results: We found a consistent pattern of socioeconomic inequalities in the risk of delivering a stillborn, mainly characterized by a persistently higher risk, over time, among women with lower SES. Overall, women from countries with low HDIs and low educational attainments had approximately a four-times higher risk of stillbirth (relative risk: 4.44; 95%CI:3.71, 5.32). Furthermore, we found a paradoxical reduction of the stillbirth gap over time between the highest and the lowest SESs, which is mostly due to the significant and increasing trend of stillbirth risk among highly educated women of advanced maternal age. Conclusion: Our findings highlight no improvement in stillbirth rates among women of lower SES and an increasing trend among highly educated women of advanced maternal age over recent years. The findings highlight the need for policymakers and health authorities to reduce health and social inequalities in stillbirth as well as the necessity of further study to understand the growing trend of age-related stillbirths among highly educated women in Spain.

Social epidemiology, Perinatal Epidemiology, Stillbirth, Population-based observational study