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

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.

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.

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.

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.