Fetal heart rate variability and monitoring in gestational diabetes mellitus: a narrative review

OBJECTIVE: To evaluate evidence on fetal heart rate variability (HRV) in pregnancies complicated by gestational diabetes mellitus (GDM), focusing on cardiotocography (CTG), computerized CTG (cCTG), fetal electrocardiography (ECG), and magnetocardio-graphy (MCG), and the influence of maternal glycemic control. STUDY DESIGN: Narrative review synthesizing clinical and experimental studies retrieved from MEDLINE, EMBASE, and SCOPUS databases. Studies evaluating fetal HRV through CTG, cCTG, ECG, and MCG in GDM pregnancies were included. RESULTS: GDM is consistently associated with altered fetal HRV, particularly reduced short-term variation, elevated baseline fetal heart rate, and impaired autonomic balance. Advanced techniques such as ECG and MCG offer superior sensitivity compared to conventional CTG, especially in pregnancies with poor maternal glycemic control. CONCLUSIONS: Fetal HRV assessment provides valuable insight into fetal well-being in GDM, suggesting potential clinical applications in antenatal monitoring. Standardization of methods and further prospective research are needed for clinical implementation.