Drinking coffee during pregnancy may increase the risk of childhood leukemia.
A recent meta-analysis from the American Journal of OB/Gyn (Feb 2014) showed that any amount of coffee consumption during pregnancy may increase the risk of childhood ALL (Acute Lymphoblastic leukemia) and AML (Acute myeloid leukemia) in offspring. The meta-analysis pooled research from both the US and overseas and found a linear association between the amount of coffee consumption and the likelihood of childhood blood cancers.
Although the risk was minimal, especially for women who drink less than 2-3 cup a day, it was enough to get me telling my newly pregnant patients that they should reduce their caffeine consumption, not only because it can reduce miscarriages but to reduce the risk of childhood cancers. Proposed theories of why caffeine may increase the risk of cancer involve caffeine’s effect on top II inhibitors which help in gene replication, and the effect it has on p53 which is a tumor suppressor.
The caffeine effect was greatest in the European studies and in studies where the women did not self-report through questionnaires and instead were interviewed. But what exactly is that risk? Well, for moderate drinkers compared to never/lowest level drinkers the increase was 22% higher, and for high level drinkers compared to the lowest level there was a 72% increase in childhood leukemia. Since leukemia is the most common childhood cancer and over 100,000 children <15 years die each year, helping women quit caffeine in pregnancy is a noble objective.