Many of us drink a cup of coffee in the morning to jumpstart our day, and continue this addictive behavior throughout the day. One cup becomes two cups, and two cups becomes three cups, and so on and so forth. The enticing aroma of coffee, or simply consuming coffee, could be a pregnancy craving for many expectant moms and a potentially dangerous habit for the next nine months. According to a recent study published in the American Journal of Obstetrics & Gynecology, drinking more than two cups of coffee a day during pregnancy increases an unborn baby’s risk of childhood leukemia by 60 percent. More than that, and the risk rises to over 70 percent.

Caffeine is known to pass back and forth across the placenta, meaning the unborn baby will come in contact with caffeine consumed by the mother. While an expectant mother’s body can handle amounts of caffeine, the baby cannot. This is because the baby’s metabolism is still maturing, says the American Pregnancy Association. Therefore, it cannot fully metabolize the caffeine. Moreover, any amount of caffeine can also trigger changes in the baby’s sleep pattern or normal movement pattern in the later stages of pregnancy, since coffee is a stimulant.

Researchers believe caffeine can act as a “DNA inhibitor or a carcinogen metabolism inhibitor,” possibly altering the DNA of a fetus’s cells, which can make an unborn baby susceptible to childhood leukemia. Denis Henshaw, Emeritus Professor of Human Radiation Effects at Bristol University, suggests the popularity of coffee and coffee shops can help explain the rise in childhood leukemia rates over recent years. "Coffee drinking has become popular, with well known coffee shops expanding, so coffee drinking has ­become very fashionable in the UK," said Henshaw, Express reported.

To explore the association between coffee consumption and the incidence of childhood leukemia, a team of researchers did a meta-analysis of more than 20 existing studies that have observed childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), with respect to maternal coffee consumption during pregnancy. The studies only observed coffee consumption but did not take into account the size of the coffees consumed or how it was prepared. Non-coffee caffeine consumption was not taken into account either. The researchers did not control for alcohol consumption in any of the pregnancies.

The findings revealed childhood leukemia risk rose to 60 percent when mothers drank more than two cups of coffee a day. Those who had four or more cups a day, increased their child’s risk of leukemia by 72 percent. “These are robust findings of an ­association between drinking coffee in pregnancy at relatively low levels and a measured increase in leukemia in your offspring,” Henshaw said.

The incidence of childhood leukemia has increased in recent decades, accounting for almost one out of three cancers, with 15,780 children and adolescents ages 0 to 19 years will be diagnosed with cancer this year. Henshaw suggests the increase in childhood leukemia rates is not genetic, since they do not change on that type of time scale, as it takes tens of thousands of years to change their genetic profile. He hints at some environmental factor, and there can be more than one of them.

Currently, three out of four leukemias among children and teens are acute lymphocytic leukemia (ALL). Most of the rest of the cases are acute myelogenous leukemia (AML), according to the American Cancer Society. Environmental factors that affect people susceptible to leukemia include those exposed to very high levels of radiation, such as survivors of a nuclear reactor accident. Also, exposure to certain chemicals such as benzene, found in gasoline and used by the chemical industry, is linked to an increased risk of some kinds of leukemia.

Tory MP Andrew Percy, who sits on the Commons Health Select Committee said: “If there are robust findings which show an association between drinking coffee during pregnancy and leukemia, then it makes sense that guidance be issued to women so they can make an informed choice about whether to drink coffee when expecting,” the Daily Mail reported.

While the study still warrants further investigation, it’s better to err on the side of caution. During pregnancy, the less caffeine you consume, the better. Moderate levels of caffeine have not been found to have a negative effect on pregnancy. Moderate consumption of caffeine varies from 150 to 300 milligrams a day, according to the American Pregnancy Association. It’s best to talk to your health care provider to decide what the healthiest choice is for you and your baby.

Source: Fan D, Cheng J, Hong Sm et al. Maternal coffee consumption during pregnancy and risk of childhood acute leukemia: a metaanalysis. American Journal of Obstetrics & Gynecology. 2014.