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Published on: September 5, 2011
Hemoglobin concentration in multiple versus singleton pregnancies--retrospective evidence for physiology not
A Krafft1, C Breymann, J Streich
1Clinic of Obstetrics, Department of Obstetrics and Gynaecology, Division of Perinatal Physiology, University Hospital Zurich, Frauenklinikstrasse 10, CH 8091, Zurich, Switzerland. alexander.krafft@fhk.usz.ch
Objective:
To describe hemoglobin (Hb) levels and percentiles for multiple pregnancies and to compare them with reference ranges of singleton pregnancies as published by the Center for Disease Control.
Study Design:
Maternal hemoglobin and red cell indices were compared: (a) between multiple and singleton pregnancies of our hospital and (b) with trimester-specific cut-offs for singleton pregnancies obtained from literature.
Results:
While early pregnancy hemoglobin values were similar in multiple and singleton pregnancies, second trimester values decreased much faster in multiple pregnancies. Nadir in multiple pregnancies was reached in weeks 24-28 of gestation. In the third trimester mean hemoglobin values were higher in multiple pregnancies, while 5th and 10th percentile were still lower compared to singleton pregnancies at term. The mean whole-pregnancy hemoglobin exceeded the Center for Disease Control (CDC) cut-off for anemia in singleton pregnancies (fifth percentile) and red cell indices remained constant.
Conclusion:
We conclude that with a significantly lower fifth percentile than introduced by the CDC in all trimesters, there should be different cut-offs for anemia in multiple pregnancies considered. A more pronounced decrease in multiple pregnancy hemoglobin levels seems to be physiological.
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