Future risk of cancer in women who have children with birth defects.

PURPOSE

We studied whether having an infant with birth defects was associated with the risk of maternal cancer.

METHODS

We carried out a longitudinal cohort study of 1,214,506 women who delivered infants between 1989 and 2016 in Quebec, Canada. We identified women whose infants had birth defects and followed the mothers over time to identify cancers up to 28 years after delivery. We used Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between birth defects and maternal cancer, adjusted for maternal characteristics.

RESULTS

A total of 36,050 women developed cancer during 19,251,851 person-years of follow-up. Relative to no birth defects, women whose infants had defects did not have an elevated risk of cancer overall (HR 1.03, 95% CI 0.99-1.06). However, associations were present with placental cancer (HR 2.23, 95% CI 1.04-4.77) and lymphoid leukemia (HR 1.61, 95% CI 1.03-2.51). Among specific birth defects, women whose infants had heart (HR 1.12, 95% CI 1.03-1.21) or sensory (HR 1.16, 95% CI 1.04-1.30) defects had a higher risk of cancer.

CONCLUSIONS

We found inconsistent evidence of a clinically meaningful association between having an infant with birth defects and the risk of early maternal cancer.