Because a deficiency of folic acid, or folate, can lead to birth defects, pregnant women are encouraged to consume foods rich in the substance or to take supplements. There's another reason for expectant mothers to pay attention to folate: Even a little extra appears to reduce the risk that the child will develop leukemia.
Judith R. Thompson of the Cancer Foundation of Western Australia in West Perth and her colleagues followed 83 children under the age of 15 who had acute lymphoblastic leukemia, and twice the number without the disease. The most common childhood cancer in industrialized countries, this cancer has been associated with parental exposure to toxic and infectious agents, genetic variations (SN: 11/6/99, p. 293), and several other factors.
The researchers questioned the children's parents about family members' personal and medical histories, including dozens of factors with known or suspected links to the leukemia. The team also recorded data about other fac