The grades of evidence (I-III) and levels of recommendation (A-C) are defined at the end of the "Major Recommendations" field.
The following conclusion is based on good and consistent scientific evidence (Level A):
- Iron supplementation decreases the prevalence of maternal anemia at delivery.
The following recommendations and conclusions are based on limited or inconsistent evidence (Level B):
- Iron deficiency anemia during pregnancy has been associated with an increased risk of low birth weight, preterm delivery, and perinatal mortality.
- Severe anemia with maternal hemoglobin (Hgb) levels less than 6 g/dL has been associated with abnormal fetal oxygenation resulting in nonreassuring fetal heart rate patterns, reduced amniotic fluid volume, fetal cerebral vasodilatation, and fetal death. Thus, maternal transfusion should be considered for fetal indications.
The following recommendations are based primarily on consensus and expert opinion (Level C):
- All pregnant women should be screened for anemia, and those with iron deficiency anemia should be treated with supplemental iron, in addition to prenatal vitamins.
- Patients with anemia other than iron deficiency anemia should be further evaluated.
- Failure to respond to iron therapy should prompt further investigation and may suggest an incorrect diagnosis, coexisting disease, malabsorption (sometimes caused by the use of enteric-coated tablets or concomitant use of antacids), noncompliance, or blood loss.
Grades of Evidence
I: Evidence obtained from at least one properly designed randomized controlled trial.
II-1: Evidence obtained from well-designed controlled trials without randomization.
II-2: Evidence obtained from well-designed cohort or case–control analytic studies, preferably from more than one center or research group.
II-3: Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled experiments also could be regarded as this type of evidence.
III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.
Levels of Recommendations
Level A - Recommendations are based on good and consistent scientific evidence.
Level B - Recommendations are based on limited or inconsistent scientific evidence.
Level C - Recommendations are based primarily on consensus and expert opinion.