Non-Linear Association of Serum Sex Hormone Binding Globulin Concentration with Female Infertility.

BACKGROUND: Accumulating proofs suggested that disturbance of serum sex hormone-binding globulin (SHBG) concentration can affect the reproductive system. However, the effect of serum SHBG on female infertility remains to be clarified. METHODS: Data from 1,787 adults from the National Health and Nutrition Examination Survey (NHANES) was applied to examine the correlation between serum SHBG and female infertility. Multivariate logistic regression was used to evaluate the independent association between serum SHBG and female infertility. Furthermore, generalized additive model (GAM) and two-piecewise linear regression model were applied to assess the underlying non-linear association in our participants. RESULTS: We observed a reverse association between serum SHBG and infertility based on a fully-adjusted model (OR = 0.99, 95% CI: 0.99-1, p = 0.002), and the results were stable in several sensitive analyses. Furthermore, we detected a non-linear link by GAM and two-piecewise linear regression model. A protective association was observed at < 58.84 nmol/L serum SHGB; in contrast, no statistical link was found at > 58.84 nmol/L serum SHGB. CONCLUSIONS: Our results provide evidence for a non-linear association with serum SHBG and female infertility. This finding needs to be further confirmed in future large-scale prospective cohort studies.

Elevated HbA1c Level has a Linear Association with Infertility in Women.

BACKGROUND: Hemoglobin A1c (HbA1c) is commonly known as a plasma glucose monitoring indicator. However, the relationship between HbA1c and fertility has not been clarified in previous literature. This study aims to investigate the association between HbA1c and the incidence of infertility. METHODS: Data from the U.S. National Health and Nutrition Examination Survey (NHANES) 2013 - 2018 was utilized. The final study contained 3,319 women aged 18 to 45 years. Multivariable logistic regression models were performed to analyze the correlation of HbA1c on female infertility with adjustment for relevant covariates including demographic characteristics, lifestyle, clinical laboratory biomarkers, and comorbidities. RESULTS: We found a significant linear correlation between HbA1c and infertility even in the fully-adjusted model (OR: 1.27, 95% CI: 1.07 - 1.5). Subgroup analysis stratified by age showed a significant linear association with HbA1c and infertility in the younger group (age < 35 years). Whereas, results showed a lack of significant association in the older group (age > 35 years). CONCLUSIONS: Data from a population-based sample in US women aged 18 to 45 years suggest that elevated HbA1c level correlated with increasing risk of infertility, even HbA1c is within the normal range. Further well-designed randomized controlled trials are needed to determine whether strategies to reduce HbA1c levels are effective in decreasing the incidence of female infertility.