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Anemia-- how do you diagnose anemia in pregnant women?

anemia | pregnant women | pregnancy | iron deficiency

Those who read our blog know that we are very focused on anemia-- and for good reason (we think). Despite increasing efforts to diagnose and treat anemia worldwide, anemia affects 28% of the global population. And for the specific populations of greatest interest to the Maternova team, anemia is of tremendous relevance-- affecting as much as 42% of pregnant women and 47% of preschool aged children internationally.

But did you know that diagnosing anemia in pregnancy requires some additional information and different cutoff points? Did you know that there are trimester specific cutoff rates for anemia? Read on!

Anemia is accompanied by symptoms including weakness, fatigue, difficulty concentrating, and
an unusual rapid heart beat. Health consequences heavily afflict pregnant women, leading to poor pregnancy outcomes and contributing to 20% of maternal deaths. Preferably, anemia is diagnosed through a complete blood count (CBC) assessment. In developing countries, methods of administering this test are costly and unattainable. Efficient testing methods have been developed in order to diagnose anemia in developing countries and primarily rely on analysis of hemoglobin levels. Haemoglobin (Hb) is a protein that is contained in red blood cells. Anemia occurs when the body does not have enough healthy red blood cells, which causes insufficient Hb resulting in an inadequate delivery of oxygen to cells in the body.

Haemoglobin levels are subject to fluctuations dependent on sex, age, pregnancy, and many other factors independent of poor intake of iron and folate-rich foods. Fluctuations in Hb naturally occur in pregnant women due to fetal and maternal biological demands. Blood volume increase by 20-30%, elevating the need for iron and other vitamins needed to create hemoglobin. This increase initiates a physiological anemia of pregnancy, the primary cause of normal mild anemia in pregnant women. These variations cause anemia threshold levels to differ for pregnant and non-pregnant women. Current cutoff values for Hb concentration
developed by the WHO can be summarized as follows

Normal non pregnant women have Hb concentration of above 12.0
Whereas for normal pregnancy women it is above 11.0

Those with severe anemia who are not pregnant are identified at <8 g/dl
Those with severe anemia who ARE pregnant are identified at < 7 g/dl

In addition to these thresholds, alternative fluctuations occur contingent on
the stage of pregnancy. Most studies agree that Hb concentrations decrease during
the first trimester, reaching their lowest levels at the end of the second trimester,
and gradually rise during the third trimester. Although mild anemia is typical
during pregnancy, severe anemia during the first two trimesters results in a higher
prevalence of anemia in the third trimester. The Centers for Disease Control have
pooled data from four European studies to in order to develop trimester-specific cut
offs based on the mid trimester values. These cut off values can be found below.
In addition, the WHO has developed Hb adjustments for diagnosis of anemia for an
unknown trimester dating. Overall, it is recognized that there is a 1.0 g/dl decrease
in Hb that takes place during the first and third trimester, with Hb concentrations
diminishing an additional .5 g/dl in the second trimester of pregnancy.

**Table 2: Trimester Haemoglobin Cut Off Values for Diagnosing Anemia

Trimester Haemoglobin
First 11 g/dl
Second 10.5 g/dl
Third 11 g/dl
Unknown dating 11 g/dl