Placental Morphometry in Relation to Daughters' Percent Mammographic Breast Density at Midlife.

Abstract Intrauterine and early-life exposures, including intrauterine smoke exposures and infant growth are associated with mammographic breast density (MBD), a strong breast cancer risk factor. We investigated whether placental morphometry, which is affected by intrauterine smoke exposure and also influences infant growth, predicts %MBD at ages 37–47. In 247 daughters in the Child Health and Development Studies, we found that larger placental surface area and placental thickness were associated with lower %MBD (−0.32 per cm2, 95% CI −0.6, −0.05; −37.8 per 0.5 cm, 95% CI= −73.3, −2.3 respectively) independent of mothers’ smoking, age, weight, parity and daughters’ birthweight and age at mammogram. We also observed a positive interaction between placental surface area and thickness (p