For couples trying to conceive, high cholesterol levels may impair fertility, according to a study by researchers at the National Institutes of Health, the University of Buffalo, and Emory University. The results from this study are published online in JCEM, the Journal of Endocrinology and Metabolism.

Study author Enrique Schisterman, PhD, chief of the Epidemiology Branch at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and colleagues theorized that blood cholesterol might affect fertility since the body uses cholesterol to make sex hormones like testosterone and estrogen.

Researchers analyzed 501 couples who were not receiving infertility treatment but were trying to conceive from 2005–2009. The couples were part of the LIFE (Longitudinal Investigation of Fertility and the Environment) study that examined the relationship between fertility and exposure to environmental chemicals and lifestyle. Study authors followed the couples until pregnancy or for up to 1 year of trying.

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Dr. Schisterman and colleagues measured the concentration of free cholesterol, which did not distinguish between cholesterol types (eg, HDL, LDL, triglycerides). The probability of a couple achieving pregnancy was calculated by the fecundability odds ratio (FOR).

They found that couples in which each partner had a high cholesterol level took the longest time to achieve pregnancy. High free cholesterol levels were correlated with longer times to pregnancy and lower fecundability odds ratios. In addition, couples where the woman had a high cholesterol level and the man did not also took longer to achieve pregnancy when compared to couples in which both partners had acceptable levels of cholesterol.

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