Structured Abstract
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.
Routine Iron Supplementation During Pregnancy
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.
These recommendations were finalized by the Task Force in January 1994
Contents
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.
Recommendations were graded as:
|
A
|
Good evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
B
|
Fair evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
C
|
Poor evidence regarding inclusion or exclusion of the condition
in a PHE, but recommendations may be made on other grounds. |
|
D
|
Fair evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
|
E
|
Good evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
Quality of evidence was rated according to 5 levels:
|
I
|
Evidence from at least 1 properly randomized controlled
trial (RCT). |
|
II-1
|
Evidence from well-designed controlled trials without randomization. |
|
II-2
|
Evidence from well-designed cohort or case-control analytic
studies, preferably from more than 1 centre or research group. |
|
II-3
|
Evidence from comparisons between times or places with
or without the intervention. Dramatic results in uncontrolled experiments
could also be included here. |
|
III
|
Opinions of respected authorities, based on clinical experience,
descriptive studies or reports of expert committees. |
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
1 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].
Validation
This guideline was adapted by the author from a review prepared by the
U.S. Preventive Services Task Force, thus their recommendations are the
same. The U.S. Surgeon General recommended that iron supplementation for
pregnant women is a "reasonable approach" to prevent anemia and also that
pregnant women should be screened and counselled for anemia. The U.S. Public
Health Service Expert Panel on the Content of Prenatal Care recommended
counselling for vitamin and iron supplements for women at risk. The Food
and Nutrition Board of the Institute of Medicine recommended routine use
of iron supplements after the 12th week of pregnancy in conjunction
with a well-balanced diet and screening for and treatment of anemia.
Sponsors
The Canadian Task Force on Preventive Health Care
developed this guideline with funding from Health Canada.
Selected
References
Source Document
Link to Full Text of this
review
Link to Summary Table of Recommendations of this review
Link to Selected References list of this review
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