Pregnancy History and Incidence of Melanoma in Women: A Pooled Analysis

Abstract

There is evidence that pregnancy history including age at first birth and parity may play a role in risk of cutaneous melanoma in women, although, epidemiological findings are inconsistent. We conducted a collaborative analysis of these factors using the original data from ten completed case–control studies (2391 cases and 3199 controls), and assessed the potential confounding effects of socioeconomic, pigmentary, and sun exposure-related factors. We found no overall association with ever having a live birth (pooled odds ratio (pOR) 0.95, 95% confidence interval (CI) 0.67–1.35). However, we detected a reduced risk of melanoma among women with higher parity (≥5 versus no live births pOR 0.76, 95% CI 0.49–1.18, each live birth pOR 0.95, 95% CI 0.91–0.99, p trend = 0.05). Women with both earlier age at first birth (e.g., <20 years) and higher parity (e.g., ≥5 live births) had a particularly lower risk than women with later age at first birth (e.g., ≥25 years) and lower parity (e.g., <5 live births) (pOR 0.33, 95% CI 0.14–0.75). The results are compatible with an effect of reproductive history-related factors on melanoma risk, but also could reflect differences in other factors, such as sun exposure history.