Abstract Study question Is multiple sclerosis (MS) associated with diminished ovarian reserve in women? Does ovarian reserve influence multiple sclerosis progression patterns? Summary answer AntiMüllerian Hormone (AMH) is not diminished in MS patients compared to healthy matched controls. Ovarian reserve predicts multiple sclerosis patterns independently from chronological age. What is known already Population registries indicate increased childlessness in individuals with MS, but the influence of MS on ovarian reserve and the need for fertility preservation counseling are topics of ongoing debate. Notably, MS research highlights the concept of immunosenescence: with age the disease shifts from high relapse rates to disability accumulation and fewer relapses. It is uncertain whether ovarian aging, assessed through AMH, could serve as a marker of immunosenescence, offering more precise predictions of MS patterns compared to chronological age alone. Study design, size, duration This prospective observational study enrolled all female MS patients aged 18 to 50 presenting to the neurology service between June and November 2023, matching them in a 1:2 ratio with controls of similar age and BMI. The controls were healthy females, without known causes of female infertility. Exclusion criteria were: postmenopausal state, prior neoplasm requiring gonadotoxic therapy or prior hematopoietic stem cell transplantation. Participants/materials, setting, methods The study was conducted in an academic hospital, regional referral for neurology and fertility preservation. Detailed neurological and gynecological anamnesis was collected for 73 patients and 146 controls. AMH measurements were performed by the same laboratory with the Roche Elecsys AMH system. Multiple generalized linear models were carried out to explore the correlation between AMH and neurological data. All results were adjusted for age and use of hormonal contraception. Bonferroni corrected post-hoc analyses were performed. Main results and the role of chance Cases and controls were matched for age (33.6±6.1 vs. 34.4±4.5 years) and BMI (22.3±3.4 vs. 22.2±3.5 Kg/m2). The AMH values were not significantly different between cases and controls (2.7±3.5 vs. 2.7±1.6 ng/ml, p = 0.7) and showed no correlation with MS duration (p = 0.3) and disability measured with EDSS score (p = 0.9). Interestingly, higher AMH levels correlated with both having relapsed in the prior year (yes: 4.9±5.3 vs. no: 1.7±1.6 p = 0.008) and with the number of relapses in the 2 previous years (zero: 1.9±1.8, one: 2.3±2.9, more than 2: 5.8±6.2 ng/ml, p = 0.02). Consequently, patients with “No Evidence of Disease Activity”(NEDA) in the previous year showed lower AMH levels (1.68±1.3 vs. 4.1±4.7 ng/ml, p = 0.01), since absence of relapses is one of the components to define NEDA. In summary, patients with higher ovarian reserve showed a MS pattern typical of young age (higher relapse rates) independently from the actual chronological age. Limitations, reasons for caution The results should be confirmed by larger/multicenter datasets, powered to properly assess the possible influence of the different disease modifying therapies. Further research is warranted to understand the biological link behind the observed results. Wider implications of the findings Ovarian aging, measured through AMH, may provide a better indicator of a patient’s biological age than chronological age only. This may help neurologists in predicting MS patterns and treating it accordingly, providing a unique perspective on the mechanisms that link immunosenescence to the ovarian reserve reduction. Trial registration number Not Applicable