Pregnancy loss, which is defined as the loss of an intrauterine pregnancy before viability, is one of the most prevalent pregnancy-related complications impacting women of reproductive age. The overall risk of pregnancy loss is 15.3 %, and the actual rate may be substantially greater in these regions as early pregnancy loss is often overlooked [1]. The likelihood of pregnancy loss is affected by a range of physiological and socio-demographic factors, in particular parity, maternal age, employment and access to reproductive health services [2]. Numerous studies have indicated the association between pregnancy loss and factors including endocrine disorders, anatomical and genetics problems, viral infections, thrombosis and immunologic derangement [3]. In addition, lifestyle and dietary habits may also play a role in the occurrence of pregnancy loss [4]. Pregnancy loss is likely to cause dysfunction of the female reproductive system, and even subsequent infertility [3,5]. In addition, pregnancy loss carries not only high medical and social costs, but also the possibility of psychological bereavement and trauma in couples [6], which has long-term consequences for both individuals and the society.

Although tremendous interventions have been applied to reduce the incidence rate and the comorbidities, pregnancy loss imposes a substantial economic burden on society. For example, the annual cost of pregnancy loss was £471 million in the UK [7]. The direct cost of management medical services of pregnancy loss was £1067 in Hong Kong [8] and £380 in the USA, in which the costs for medical management was £298 [9]. It has been reported that service costs for surgical management was £2242 in Spain [10], and £455 in Finland [11]. These data indicated that the financial burden attributed to pregnancy loss varied greatly, and was substantial. Therefore, comprehensive and up-to-date epidemiological data is indispensable for policymakers and academics to identify the regional disparities, and develop targeted strategies. The Global Burden of Disease (GBD) 2021 emphasizes new and existing health threats that need to be prioritized on the international public health agenda [12]. Although the data in Global Burden of Disease (GBD) 2019 was analyzed [13], no new systematic review of pregnancy loss was conducted based on GBD 2021. To refine the global pregnancy loss burden data, we drew on the latest GBD 2021 data and extended the work by employing a variety of analytical methods. Specifically, in addition to the use of decomposition analysis and a cross-country health inequality analysis, we also applied the age-period-cohort model to further analyze the influence of age, period, and birth cohort on incidence changes in pregnancy loss over the past 30 years, to gain insight into the global burden of pregnancy loss.