Relationships of vitamin D and oxidized low-density lipoprotein with infertility in patients with polycystic ovary syndrome based on restricted cubic spline models

Objective To explore the relationships of vitamin D and oxidized low-density lipoprotein (ox-LDL) with infertility in patients with polycystic ovary syndrome (PCOS) based on restricted cubic spline models.

Methods A total of 150 PCOS patients were selected as the study subjects and followed up for at least 1 year. They were divided into infertile group and non-infertile group according to whether they were infertile. A Logistic regression model was used to analyze the influencing factors of infertility in PCOS patients. Furthermore, the relationships of 1, 25-dihydroxyvitamin D₃1, 25-(OH)₂D₃ and ox-LDL with infertility in PCOS patients, as well as their interactive effects on infertility in PCOS patients were analyzed. A restricted cubic spline model was used to analyze the non-linear relationships between 1, 25-(OH)₂D₃, ox-LDL, and infertility in PCOS patients.

Results Among 150 PCOS patients, 78 were not pregnant, resulting in an infertility rate of 52.00%(78/150). Multivariate Logistic regression analysis showed that the severity of PCOS, body mass index, age, 1, 25-(OH)₂D₃, and ox-LDL were all independent influencing factors for infertility in PCOS patients (P < 0.05). After adjusting for confounding factors, 1, 25-(OH)₂D₃ and ox-LDL were still associated with the risk of infertility in PCOS patients (P < 0.05). Restricted cubic spline model analysis revealed non-linear relationships between 1, 25-(OH)₂D₃, ox-LDL, and the risk of infertility in PCOS patients (P < 0.05). When the serum 1, 25-(OH)₂D₃ level was < 35.70 nmol/L, it was negatively correlated with the risk of infertility in PCOS patients (P < 0.05). When the serum ox-LDL level was ≥381.00 μg/L, it was positively correlated with the risk of infertility in PCOS patients (P < 0.05). Interactive effect analysis showed that 1, 25-(OH)₂D₃ and ox-LDL had antagonistic effects on infertility in PCOS patients (P < 0.05).

Conclusion Decreased serum 1, 25-(OH)₂D₃ levels and increased ox-LDL levels in PCOS patients can significantly increase the risk of infertility. Moreover, there is a non-linear dose-response relationship and an antagonistic interactive effect between them, suggesting that regulating vitamin D and oxidative stress levels may be an important strategy for improving the fertility outcomes of PCOS patients.