Childhood Nonlymphoid Leukemia Risk With Maternal Use of Hormonal Contraception
In a population-based cohort study reported in The Lancet Oncology, Hargreave et al found that recent maternal use of hormonal contraception was associated with increased risk of childhood nonlymphoid leukemia.
Study Details
The study involved data from a nationwide cohort of 1,185,157 live-born children between 1996 and 2014 from the Danish Medical Birth Registry, with identification of those diagnosed with leukemia obtained from the Danish Cancer Registry. Data from the Danish National Prescription Registry provided information on maternal hormonal contraceptive use, categorized as: no use (never used contraception before birth; reference category), previous use (> 3 months before start of pregnancy), and recent use (≤ 3 months before and during pregnancy).
Exposure and Risk of Leukemia
The 1,185,157 live-born children represented a total of 11,114,290 person-years of follow-up, with median follow-up of 9.3 years. During follow-up, 606 children were diagnosed with leukemia, including 465 with lymphoid leukemia and 141 with nonlymphoid leukemia. Children born to women with previous use of hormonal contraception (hazard ratio [HR] = 1.25, P = .039) and recent use (hazard ratio [HR] = 1.46, P = .011) were at increased risk of any leukemia vs children of women with no contraception use; among the subgroup with hormonal contraception use during pregnancy, risk of childhood leukemia was numerically greater (HR = 1.78, P = .070). No significant associations were observed between previous use (HR = 1.23, P = .089) or recent use (HR = 1.27, P = .167) and risk for lymphoid leukemia. Risk for nonlymphoid leukemia was significantly increased with recent use (HR = 2.17, P = .008) and use during pregnancy (HR = 3.87, P = .006) vs no use; when compared with previous use, risk associated with recent use remained significantly elevated (P = .03).
It was estimated that hormonal contraception use close to or during pregnancy might have resulted in one additional case of leukemia per approximately 50,000 exposed children, representing 25 additional cases during the 9-year study period.
The investigators concluded, “Our findings suggest the maternal hormonal use affects nonlymphoid leukaemia development in children. Since almost no risk factors have been established for childhood leukaemia, these findings suggest an important direction for future research into its causes and prevention.”
The study was funded by The Danish Cancer Research Foundation, Arvid Nilssons Foundation, Gangsted Foundation, Harboe Foundation, and Johannes Clemmesens Foundation.
Marie Hargreave, PhD, of the Danish Cancer Society Research Center, Copenhagen, is the corresponding author for The Lancet Oncology article.
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