Addressing multiple pregnancies in in vitro fertilization-embryo transfer: Current status, challenges, and solutions.

With the rising global incidence of infertility and the growing proportion of infants conceived via in vitro fertilization-embryo transfer (IVF-ET), multiple pregnancies have emerged as a prominent and pressing challenge in assisted reproductive technology. This review synthesizes evidence from clinical, ethical, and technological research to comprehensively analyze the current status and underlying causes of and the potential solutions to this issue. Despite global efforts to curb it, the multiple pregnancy rate in IVF-ET remains persistently high, with significant regional disparities primarily driven by variations in the adoption of single embryo transfer (SET), a key strategy for reducing multiple pregnancies. The widespread implementation of SET is hindered by a long-standing clinical dilemma: its lower clinical pregnancy rate (CPR) compared to double embryo transfer (DET), which leads clinicians and patients to prefer DET despite the associated risks. The fundamental resolution to this impasse lies in enhancing the accuracy of embryonic developmental potential assessment. Currently, two technological directions show substantial promise: the integration of time-lapse imaging with artificial intelligence for objective morphological and kinetic evaluation, and the continuous advancement of molecular biology techniques (e.g., non-invasive preimplantation genetic testing and multi-omics-based biomarker screening). While no transformative breakthroughs have been achieved to date, the ongoing refinement of these technologies, coupled with standardized clinical practices and multicenter validation, offers significant potential to optimize SET success rates, narrow the CPR gap with DET, and ultimately address the multiple pregnancy challenge in IVF-ET at its source.