There are several possibilities, depending how far into the pregnancy you are, any symptoms you are having and if there was an underlying condition unrelated to pregnancy.
Low kidney function
UTI / bladder infection.
Pre-eclampsia
Hemoglobin
It is Hemoglobin
Sickle cell hemoglobin differs from normal hemoglobin primarily due to a single amino acid substitution in the hemoglobin protein chain. In sickle cell disease, a person inherits two copies of an abnormal hemoglobin gene, usually referred to as HbS. In normal hemoglobin (HbA), the amino acid glutamic acid is present at a specific position in the beta chain of the hemoglobin protein. However, in sickle cell hemoglobin (HbS), this glutamic acid is replaced by valine due to a genetic mutation. This change causes the hemoglobin molecules to stick together under certain conditions, forming long, rigid structures that distort red blood cells into a sickle or crescent shape.
If our hemoglobin gene is normal, the hemoglobin protein works fine. But if the instuctions in that gene are changed, or "mutated,"changes in the hemoglobin protein could result. One such mutation causes a disorder called sickle cell anemia.
normochromic
That protein is called denatured.
NORMOCHRONIC
For an infant, normal hemoglobin is 14-22 g/dL
Hemoglobin is a metalloprotein, which is a generic term for a protein that contains a metal iron cofactor. (A cofactor in biochemistry terms is a non-protein chemical compound that is bound to a protein and is vital for the protein's biological activity.)
loss of only one amino acid from the normal hemoglobin molecule
There are two categories of hemoglobinopathy. In the first category, abnormal globin chains give rise to abnormal hemoglobin molecules. In the second category, normal hemoglobin chains are produced but in abnormal amounts.
Hemoglobin is that protein in the red blood cells that carries oxygen. A normal range of values in a female is: 12.1 - 15.1 gm/dl; in a male, it is 13.8 - 17.2 gm/dl. So, if one has a hemoglobin of 6.4, this is an abnormal value and should be evaluated by a physician ASAP.