Maternal genitourinary tract infection during pregnancy increases the risk that the child will develop leukaemia by more than a third, according to researchers from Denmark.

Researchers followed over 2 million children from birth for a mean of 12 years. During this time, 1,307 children were diagnosed with leukaemia. Overall, 3.7 per cent of mothers experienced at least one infection during pregnancy.

Children born to mothers who had an infection during pregnancy had a 35 per cent increased risk of leukaemia compared with controls whose mothers did not have an infection. In particular, maternal genital and urinary tract infections (UTI) were associated with a 142 and 65 per cent increased risk of childhood leukaemia respectively. The risk was more than three-fold higher (hazard ratio 3.13) among women who had a sexually transmitted infection. The absolute difference in leukaemia risk between children of infected mothers and controls was 1.8 cases for any infection, 3.4 cases for UTI and 7.1 cases for genital tract infection per 100,000 person-years.

No association emerged for infections other than genital and UTIs or between maternal infection and other childhood cancers. 

“Given that little is known about the aetiology of childhood leukaemia, these findings suggest an important direction for research … as well as [the] development of potential preventive measures,” the authors comment.