Researchers at the Medical University of South Carolina analysed population-based data from the US National Health and Nutrition Examination Surveys and found that people with elevated levels of serum transferrin saturation - an indicator of iron overload - who consume high levels of dietary iron had an increased risk of cancer and cancer mortality.

Transferrin saturation of more than 60 per cent had already been identified as a cancer risk factor but the researchers wanted to assess whether dietary iron intake increases the risk of cancer among individuals with transferrin saturation of less than 60 per cent.

Their research found that people with transferrin saturation of more than 45 per cent who ingest more than 18 mg of iron per day have a 2.24 times greater relative risk of cancer than those who have normal transferrin saturation levels and report low dietary iron intake.

Approximately 7 per cent of adults in the United States has transferrin saturation levels greater than 41 per cent placing them at more risk of cancers.

Having high transferrin saturation with a normal diet does not carry increased risk and intake of dietary iron was essentially uncorrelated with transferrin saturation.

The researchers say, simple dietary restrictions may help to reduce the cancer risk associated with high transferrin saturation, adding that their findings call into question the strategy of the addition of iron to food by manufacturers.

The research is reported in the current issue of the Annals of Family Medicine.

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The evidence that multiple visits, constant monitoring and special diets lead to better outcomes for baby and mother, however, is being questioned by new systematic reviews and large-scale analyses of available studies. For instance, a major review by the World Health Organization in 2001 found that women who visited their doctors only four times during their pregnancy were comparable to those who had 12 or more visits in rates of pre-eclampsia (a dangerous form of very high blood pressure among pregnant women), postpartum anemia, low birth weights and infant and mother deaths.

Traditionally, low-risk pregnant women in the United States who participate in prenatal care have been scheduled for about 14 to 16 prenatal visits, which is the schedule recommended by the American College of Obstetricians and Gynecologists, says Deborah Walker, a clinical nursing professor at Wayne State University.

Walker says the available evidence from the WHO report and a similar study in 1989 by the U.S. Department of Health and Human Services16 suggests most women will do fine with fewer visits. But women who have been used to a certain level of care may have trouble getting used to that idea, according to the WHO report, which found that expectant mothers in developed countries like the United States were more dissatisfied with the reduced visit schedule.

Low birth weight and early delivery are among the most common pregnancy complications, and women at risk for those complications are treated with a variety of preventive measures. But according to Dr. Michael Lu of the University of California, Los Angeles School of Medicine, there is little evidence to support most of these treatments, including bed rest, childbirth education and antibiotic and hormonal treatments. Preterm births and low birth weights are not effectively prevented by prenatal care in its present form, Lu and colleagues concluded in a 2003 systematic review.

Among the other interventions offered routinely to pregnant women are ultrasound readings and nutritional advice. Yet there is scarce evidence to support either recommendation, according to recent reviews by the Cochrane Collaboration. In 2000, reviewers concluded that late term ultrasound in low-risk pregnancies does not benefit either mother or baby. A 2003 review found that there was no consistent benefit to mother or child when women ate more daily calories and grams of protein during their pregnancies.

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