Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made.  (Formerly, these situations were captured under a "C Recommendation".)  This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade.  For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.

Adapted by John W. Feightner, MD, MSc, FCFP, Department of Family Medicine, The University of Western Ontario from a review prepared for the U.S. Preventive Services Task Force by Dr. Steven H. Woolf.

Objective
To make recommendations for the routine use of oral iron supplements in Canadian women who are pregnant.

Burden of Suffering
It is estimated that about 5-10% of women aged 20 to 44 years are iron deficient. The prevalence in pregnant women is thought to be higher, but exact data are lacking. The World Health Organization defines anemia in pregnancy as a hemoglobin concentration below 110 g/L during the first and third trimesters and below 105 g/L during the second trimester, or a hematocrit less than 32%. Iron deficiency anemia is more common in certain high-risk groups, such as persons of low socioeconomic status or limited education; women with high parity, or those with a history of menorrhagia or multiple gestations; persons with diets that are low in both meat and ascorbic acid; persons who donate blood more than three times per year; adolescents; and persons who use aspirin regularly.

Among the postulated risks of iron deficiency to the mother are increased fatigue and decreased work performance, cardiovascular stress due to inadequate hemoglobin and low blood oxygen saturation, impaired resistance to infection, and poor tolerance to heavy blood loss and surgical interventions at delivery. The postulated risks on the fetus relate to the impaired delivery of hemoglobin and, thus, of oxygen to the uterus, placenta, and developing fetus. Another postulated risk is that mothers with these conditions may give birth to infants with anemia or iron deficiency and that this may result in abnormal child development if the deficiencies are not corrected early.

Options
The options are the provision or nonprovision of oral iron supplements during pregnancy. This guideline does not address concerns with a healthy diet for pregnant women, combination vitamin preparations for pregnant women, or the iron needs of newborn infants.

Outcomes
Obstetrical outcomes (preterm delivery, low birth weight, fetal death, operative delivery), hematologic indices for the mother, and need for transfusion.

Evidence
English-language observational and clinical trials published between 1966 and 1991 were sought if they measured clinical outcomes in the mother or child.  Review of the evidence focused on studies done in industrialized countries.

Values
The 13-member Task Force of experts in family medicine, geriatric medicine, pediatrics, psychiatry and epidemiology used an evidence-based method for evaluating the effectiveness of preventive health care interventions. Recommendations were not based on cost-effectiveness of options. Patient preferences were not discussed.

Background papers providing critical appraisal of the evidence and tentative recommendations prepared by the chapter author were pre-circulated to the members. Evidence for this topic was presented and deliberated upon in 1- to 2-day meetings, from April 1993 to January 1994. Consensus was reached on final recommendations.

Benefits, Harms, and Costs
One cohort study showed iron supplements improved the rate of premature delivery and increased birth weight in boys but confounding variables were not analyzed. Another prospective study found no association between low maternal hemoglobin and adverse perinatal outcomes. RCTs of iron supplements showed mixed results and often had methodological shortcomings. Iron supplements improved the hematologic indices in the mother but did not necessarily improve outcomes.

Iron supplements often have adverse effects such as new or worsening of gastrointestinal symptoms, hemochromatosis, and hemosiderosis. In addition, iron supplements are a potential source of unintentional overdose by other children in the home.

Recommendations
Recommendation grade [A, B, C, D, E]  and level of evidence [I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations in support of individual recommendations are identified in the guideline text.

• Insufficient evidence exists to recommend for or against the routine use of oral iron supplementation in pregnant women [C, II-1, II-2, I].

Sponsors
The Canadian Task Force on Preventive Health Care developed this guideline with funding from Health Canada.

Source Document
Feightner J.W. Routine iron supplementation during pregnancy. In: Canadian Task Force on the Periodic Health Examination. Canadian Guide to Clinical Preventive Health Care. Ottawa: Health Canada, 1994; 64-72.