Pregnant women often are advised to take or are prescribed iron and vitamin supplements. One new report adds to the list of benefits gained from taking prenatal vitamins, while another study compares daily iron supplementation during pregnancy with weekly supplementation.

The first paper, published in the Journal of Obstetrics and Gynaecology Canada, a metaanalysis of 41 studies, showed that prenatal vitamins fortified with folic acid cut the risk of neural tube defects by 33% in case-control studies and by 48% in cohort and randomized, controlled trials. Data also showed that prenatal vitamins lower the risk of heart defects and limb deformities. The protective effect was "less consistent" with cleft palate, urinary tract deformities, and hydrocephalus. Prenatal vitamins were found not to protect against Down syndrome, undescended testes, pyloric stenosis, or hypospadias. The researchers recommend that women who are attempting to become pregnant begin taking prenatal vitamins as soon as possible.

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In the second study, published in the Archives of Medical Research, researchers compared weekly and daily iron supplementation in 120 healthy, pregnant Mexican women. Women in the 20th week of pregnancy were prescribed tablets containing 60 mg iron, folic acid, and vitamin B₁₂ at a dosage of either one tablet daily or two tablets once weekly. Although more of the weekly users became mildly anemic (a hemoglobin level of less than 103 g/L), no hemoglobin level was low enough to cause complications. However, 11% of the daily users, compared with 2% of the weekly users, had a hemoglobin level of more than 145 g/L. Compared with women with lower iron levels, those with the highest levels were 7.8 times more likely to deliver prematurely and 6.2 times more likely to deliver low-birth-weight babies.

The problem of excessive iron intake during pregnancy receives little attention, according to study coauthor Fernando E. Viteri of the University of California, Berkeley, and Children's Hospital, Oakland Research Institute. "By looking only at anemia in pregnancy, physicians have missed the issue of excess iron intake, which could lead to premature or low-birth-weight babies," he says. Studies show that iron supplements of 120 mg weekly pose little risk for complicating pregnancy, but supplementation of60 mg daily in nonanemic women can be problematic. Viteri advises healthy, nonanemic women who are planning to become pregnant to take 60 mg of iron once weekly and then double that dose to 120 mg weekly during pregnancy.

Carol Potera

NewCAP

PET scans shed light on "chemo brain." After chemotherapy, many people report feeling confused, forgetful, and unable to concentrate, a condition commonly referred to as "chemo brain." To investigate the physiologic mechanisms that might be at work, researchers examined positron emission tomographic scans of the brains of 16 women treated with chemotherapy five to 10 years earlier for breast cancer. The investigators found that chemotherapy changes brain activity: compared with chemotherapy-free controls, the chemotherapy group showed altered activity in portions of the frontal cortex, cerebellum, and basal ganglia.

Silverman DHS, et al. Breast Cancer Res Treat 2006;Sep 29 Epub ahead of print.