Pregnancy and risk of acute myeloid leukaemia - a case-control study

Although maternal haematopoiesis is characterised by rapid proliferation and immunological adjustment, leukaemia seldom occurs in pregnant women. In this case–control study, we investigated pregnancy and risk of acute myeloid leukaemia (AML). A total of 785 women with AML diagnosed in ages 15–50 were compared with 1576 age‐ and sex‐matched controls. At the time of diagnosis, 13 cases and 53 controls were pregnant (1.3% and 3.4%, respectively), resulting in a significantly reduced odds ratio of 0.44 (95% confidence interval 0.22–0.85). Odds ratios of AML during the years following childbirth were close to unity. The results suggest that pregnancy conveys a strong short‐term protection against AML.