Association between the dietary index for gut microbiota and female infertility: The mediation effects of lymphocyte count and red blood cell folate.

Previous studies have revealed a the relationship between changes in the gut microbiota composition and female infertility. While the association between the dietary index for gut microbiota (DI-GM) and female infertility remains unstudied. The correlation was investigated with NHANES data from 2013 to 2018, with dietary recall data being used to calculate the DI-GM. Mediation analysis was performed to explore the role of lymphocyte count (LC) and red blood cell (RBC) folate in the DI-GM-induced risk of female infertility risk. Among the 1555 individuals included in our study, 311 were diagnosed with female infertility. According to the weighted binary logistic regression analyses, when all the covariates were adjusted, a negative association was observed between the DI-GM score and the risk of female infertility (OR: 0.80, 95 %CI: 0.74-0.88). After grouping participants by DI-GM score, compared with scores in the lowest quartile (Q1), the scores in Q3 and Q4 of DI-GM score were negatively associated with female infertility in crude and adjusted models, with ORs (95 %CI; P for trend) of 0.44 (0.27-0.70; <0.001); 0.43 (0.28-0.64; <0.001) and 0.43(0.26-0.71; <0.001); 0.41(0.27-0.60; <0.001). Additionally, restricted cubic splines logistic analysis uncovered a nonlinear association between the DI-GM score and the prevalence of female infertility. Mediation analysis indicated that LC and RBC folate mediated 4.64 % and 7.08 %, respectively of the association of the DI-GM scores with risk of female infertility. The nomogram exhibited good performance in this study (AUC 0.70, 95 % CI = 0.67-0.73). Our research revealed that the DI-GM score was negatively related to risk of female infertility. Mediation analyses demonstrated that LC and RBC folate levels significantly mediate the association between the DI-GM and the prevalence of female infertility.