Kimberly A Bertrand, Heather J Baer, E John Orav, Catherine Klifa, Ajay Kumar, Nola M Hylton, Erin S LeBlanc, Linda G Snetselaar, Linda Van Horn, Joanne F Dorgan

Emerging evidence suggests positive associations between serum antimüllerian hormone (AMH), a marker of ovarian function, and breast cancer risk. Body size at young ages may influence AMH levels, but few studies have examined this. Also, no studies have examined the relation of AMH levels with breast density, a strong predictor of breast cancer risk. We examined associations of early life body fatness, AMH concentrations, and breast density among 172 women in the Dietary Intervention Study in Children (DISC). Height and weight were measured at baseline (ages 8-10) and throughout adolescence. Serum AMH concentrations and breast density were assessed at ages 25-29 at the DISC06 Follow-Up visit. We used linear mixed effects models to quantify associations of AMH (dependent variable) with quartiles of age-specific youth body mass index (BMI) Z-scores (independent variable). We assessed cross-sectional associations of breast density (dependent variable) with AMH concentration (independent variable). Neither early life BMI nor current adult BMI was associated with AMH concentrations. There were no associations between AMH and percent or absolute dense breast volume. In contrast, women with higher AMH concentrations had significantly lower absolute non-dense breast volume (p-trend <0.01). We found no evidence that current or early life BMI influences AMH concentrations in later life. Women with higher concentrations of AMH had similar percent and absolute dense breast volume, but lower non-dense volume. These results suggest that AMH may be associated with lower absolute non-dense breast volume; however, future prospective studies are needed to establish temporality.