Impact of Obstructive Sleep Apnea on Fetal Heart Rate: A Systematic Review

Aims/Background: Obstructive sleep apnea (OSA) and intermittent maternal hypoxia during pregnancy have been hypothesised to impact fetal heart rate (FHR). To evidence this possible link, we performed a systematic review of the current evidence about maternal OSA and FHR alteration. Methods: The following databases were analysed from the inception to June 2024: Cochrane Library, PubMed-Medline, EMBASE, Web of Science, and Google Scholar. We included studies with pregnant women affected by OSA, and FHR assessed via cardiotocography or fetal electrocardiography. Studies without polysomnography or home sleep testing, cross-over designs, or non-English publications were excluded. Results: 168 studies were screened, and six were included. Five were prospective observational studies, and one was a case report. Maternal age showed a value from 26.6 ± 7.1 to 34.8 ± 3.3 years, and gestational age ranged from 32.1 ± 3.4 to 39.4 ± 1.0 weeks. The body mass index (BMI) values ranged between 27.5 ± 7.2 and 55 kg/m2. Polysomnography was the primary diagnostic tool for OSA in most studies; one study utilised a home sleep test. Apnea/hypopnea episodes frequency varied from 8.4 to 159 events per hour. Findings about the FHR alterations were discordant: three studies did not report an association, other three observed FHR changes linked to maternal respiratory events. Conclusion: Our systematic review evidenced a significant variability about the maternal OSA impact on fetal heart rate. The study’s results were contradictory. These inconsistencies also derive from different study designs, sample sizes, and outcomes analysed. Further studies are necessary to evidence the real impact of the OSA on the fetal cardiac response. Systematic Review Registration: PROSPERO (CRD42024533801).