JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):148
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263941

P-136. Impact of night-shift work on hormonal balance, epigenetic aging, and reproductive health in female and male healthcare workers

Roberta Bellinghieri¹, Claudia Ferraro¹, Laura Sichenze¹, Elena Trombetta¹, Arianna Nani¹, Vittoria Sterpi¹, Laura Porretti¹, Maira Casalechi¹, Paola Vigano¹

¹ Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano - - Italy

Objective: Night-shift work disrupts circadian rhythms, potentially impairing hormonal regulation and reproductive function. While evidence suggests associations with infertility, menstrual disturbances, and adverse obstetric outcomes in women, and altered semen parameters and testosterone levels in men, the mechanisms remain unclear. This study aimed to evaluate the impact of night-shift work on steroid hormone profiles, biological aging in women, and seminal parameters in men to determine whether night shifts impair reproductive health through hormonal or epigenetic alterations.
Methods: This prospective case-control study included 93 female (<43 years) and 62 male (<50 years) healthcare workers recruited at our hospital between June 2023 and March 2024. Participants were grouped into cases (≥1 night shift/week in the previous 3 months) and controls (no night shifts). Vacation within the last 3 months was an exclusion criterion. For females (n=44 cases, n=49 controls), blood samples were collected on the 3rd day of the menstrual cycle. Steroidal hormones were analyzed via HPLC-MS. DNA methylation (DNAm) was assessed using qPCR, and biological age was calculated using the Zbieć-Piekarska2 epigenetic-age model. Epigenetic age acceleration (EAA) was estimated using residuals from a linear regression of DNAm age on chronological age. For males (n=31 cases, n=31 controls), both blood and semen samples were collected. Hormonal analysis followed the same HPLC-MS protocol. Seminal parameters (concentration, motility, morphology) were assessed per WHO guidelines, and sperm DNA fragmentation index (DFI) was measured via flow cytometry.
Results: In females, no significant differences were found between cases and controls regarding BMI, smoking, alcohol consumption, comorbidities, or contraceptive use. Night-shift workers were slightly younger than controls (29 [22–33] vs. 30 [27–36] years, p=0.04). No significant hormonal differences were observed between groups not using hormonal contraceptives. DNAm age was lower in night-shift workers (28 [24–33] vs. 33 [26–39] years, p=0.04), but epigenetic age acceleration did not differ significantly (-1.62 [−7.16–3.66] vs. 0.93 [−3.78–4.83], p=0.20), suggesting no adverse impact of night shifts on biological aging. In males, night-shift workers were older (34 [29–39] vs. 30 [27–31] years, p=0.005) and had a higher BMI (23.4 [22.3–26.1] vs. 22.3 [21.0–24.0], p=0.03). No significant differences were found in sperm concentration, total count, progressive motility, morphology, or DFI. However, night-shift workers had significantly lower cortisol (109.4 [74.5–135.8] vs. 138.5 [96.7–168.2], p=0.02) and DHEA-S levels (1,909.5 [1,346.6–2,254.7] vs. 2,332.1 [1,805.2–2,785.0], p=0.01), indicating some degree of hormonal dysregulation.
Conclusion: Preliminary findings suggest that night-shift work does not significantly impair reproductive potential in female or male healthcare workers from a clinical standpoint. In women, the absence of major disruptions in steroid hormone profiles or epigenetic age acceleration indicates that circadian misalignment may not directly compromise epigenetic aging or immediate fertility potential. In men, despite stable semen parameters, the observed alterations in cortisol and DHEA-S highlight subtle endocrine imbalances that could have long-term implications for reproductive function, particularly under stress or in subfertile populations. These results are clinically relevant as they suggest that routine night-shift work alone may not necessitate altered ART management strategies in otherwise healthy individuals. However, the identified hormonal shifts, especially in men, may justify closer hormonal monitoring in couples presenting for assisted reproduction where night-shift work is a factor. Ongoing analysis with larger cohorts and reproductive outcomes will clarify whether night shifts contribute to subclinical fertility dysfunction or reduced reproductive success rates over time.