Placental weight and breast cancer risk in young women: A registry-based cohort study from Norway
Cancer Epidemiology, Biomarkers & Prevention, 06/15/2012
Opdahl S et al. – We could not confirm previous reports that women who develop large placentas are at increased risk of breast cancer.Methods
- In a cohort of 338,051 women followed from 1999 to 2008, on the basis of data linkage between the Medical Birth Registry of Norway and the Cancer Registry of Norway, we assessed whether placental weight in a woman's most recent pregnancy was related to breast cancer risk during the first years following pregnancy.
- During follow-up (median, 6.0 years; interquartile range, 3.0–8.3 years), 648 women were diagnosed with breast cancer at a mean age of 38.4 years (standard deviation, 5.3 years).
- Placental weight in the most recent pregnancy was not associated with breast cancer risk: the hazard ratio per 100-gram increase in placental weight was 1.03 [95% confidence interval, 0.96–1.10].
- There was a similar lack of association related to mean placental weight across pregnancies and to placental weight associated with the first birth.