PCOS linked to lower heart rate variability

Polycystic ovary syndrome is one of the most common endocrine disorders in women of reproductive age, and it reaches well beyond the ovaries: it is tied to insulin resistance, impaired glucose tolerance and dyslipidaemia. Heart rate variability, the beat-to-beat variation in heart rhythm, is a widely used marker of autonomic nervous system function, and reduced HRV has been associated with adverse cardiovascular events. Individual studies have hinted at altered autonomic drive in PCOS, but results have been scattered. This review set out to answer a clear question: taken together, does the evidence show that cardiac autonomic function is genuinely different in women with PCOS?

The authors conducted a systematic review and meta-analysis following PRISMA guidelines, searching PubMed, Scopus, Web of Science and Cochrane for studies comparing HRV in women with PCOS against controls. Risk of bias was assessed with the ROBINS-I tool and the certainty of evidence was graded using the GRADE approach. Seventeen articles met the inclusion criteria, varying in quality from low to high risk of bias. The team pooled standardised mean differences using a random-effects model, ran subgroup analyses to probe the high heterogeneity, and checked the robustness of the results with sensitivity analysis.

Combined analyses showed a notable decrease in HRV among women with PCOS compared with controls. Time-domain measures fell significantly, including SDNN (SMD -0.763) and PNN50 (SMD -1.245), as did total power (SMD -1.997) and high-frequency power in normalised units (SMD -0.873). Meanwhile the LF/HF ratio (SMD 0.670) and normalised low-frequency power (SMD 0.840) rose significantly. Subgroup analysis added a twist: the HRV alterations were significant in normal-weight and overweight women with PCOS, but no significant changes were observed in the obese PCOS subgroup. Study design explained part of the heterogeneity between studies.

This pooled analysis strengthens earlier individual studies suggesting altered autonomic drive in PCOS, moving the idea from scattered signals to a consistent overall pattern across 17 studies. It also complicates the picture: the null finding in the obese subgroup is counterintuitive, since obesity itself is usually linked to lower HRV, and the abstract does not explain why. The included studies varied in quality and heterogeneity was high, so the size of the effect remains uncertain. Whether reduced HRV in PCOS translates into more cardiovascular events over time, and whether treating PCOS restores autonomic balance, are open questions this analysis cannot answer.

If you have PCOS and track HRV through a wearable, this is useful context: a lower baseline than your peers may partly reflect the condition itself rather than poor recovery alone. More broadly, the finding is a reason to think of PCOS as a whole-body condition with a cardiovascular dimension, not purely a reproductive or hormonal one. Because this is associational evidence from studies of mixed quality, it cannot say that PCOS damages the autonomic nervous system or that any intervention would reverse the pattern, but it does add weight to keeping an eye on heart health alongside the more familiar metabolic side of PCOS.