|IRON DEFICIENCY ANEMIA AND PREGNANCY|
Zhou SJ, Gibson RA, Crowther CA, Makrides M. Should we lower the dose of iron when treating anaemia in pregnancy? A randomized dose-response trial. Eur J Clin Nutr 2009;63:183-90.
This was a double blind placebo randomized trial looking at the supplementation of iron for pregnant anemic women. Anemia was defined as hemoglobin [Hgb] less than 11.0 g/100 ml. Iron (Fe), as ferrous sulfate, was given in 3 different doses, 20 mg/day, 40 mg/day, or 80 mg/day for 8 weeks during mid-pregnancy.
Hgb at baseline measured an average of 10.4 g/100 ml. In response to supplementation, Hgb levels showed evidence of a dose-dependent increase. As Fe dose increased, Hgb levels increased. At the end of the trial, 38% of women assigned to the 20 mg dosage were still anemic compared with 26% in the 40 mg dosage group and 24% in the 80 mg dosage group. But these differences were not statistically significant.
Gastrointestinal (GI) side effects were significantly less common in those women taking the lowest dose. Specifically, there was 60% less nausea, 70% less stomach pain, and 60% less vomiting in the lowest-dose group. These differences were all statistically significant.
Previous research has suggested that low-dose (e.g., 18-30 mg/day) Fe may be almost as effective as higher doses in preventing anemia in pregnant women. Due to the frequency and intensity of side effects from the Fe that doctors give pregnant women it can be very difficult for pregnant anemic women to comply with supplementation recommendations.
Incidence of anemia in the low-dose group (38%) was approximately 50% higher than the 24-26% incidence reported in the two groups receiving the higher doses.
These researchers think that it makes sense to use "low-dose" Fe. This may be in part due to the GI side effects of large doses of ferrous sulfate—the common form used by most MDs. The problem is that while the 40 mg dosage was essentially as effective as the 80 mg dosage in eradicating anemia, it wasn't very effective in reducing side effects. The 20 mg dosage clearly produced the fewest side effects, but the incidence of residual anemia remained much higher even though that difference was not statistically significant.
Most of my pregnant patients have been able to tolerate the Fe I recommend. I and many other nutritionally trained practitioners have the knowledge to use more easily absorbed iron forms, instead of ferrous sulfate. This makes it easier for pregnant women to be comfortable and replete their iron status.
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