“Normal” changes in blood test results during pregnancy
A normal pregnancy is regularly accompanied by certain alterations at the level of some blood tests, also called “physiological”. It is also important to know these “physiological” haematological variations in order to be able to correctly distinguish them from the possible onset of pathological conditions.
Anemia , by definition, is given by a drop in the total hemoglobin levels in our body, together with a drop in the red blood cell count ; the World Health Organization has defined a hemoglobin value below 11 g/dL as anemia in pregnancy.
Physiological anemia of pregnancy
Starting from the 6th week of pregnancy there is a regular rapid and significant increase in the volume of the liquid part of the blood (i.e. plasma) and, to a lesser extent, an increase in the volume of red blood cells (i ) . These modifications induce a dilution of the blood which facilitates the exchange of oxygen and nutrients between mother and fetus but, at the same time, involves a drop in hemoglobin levels (generally up to 10-11 g/dL); this condition is also defined as “physiological anemia of pregnancy” (or hemodilution anemia) .
Furthermore, during pregnancy there is an increased need for iron and folic acid; in this regard, in order to prevent the onset of deficiency anemia due to iron and folate deficiency, an adequate intake of these substances is recommended.
Thrombocytopenia in pregnancy
Frequently, at the end of the third trimester of pregnancy, there is also a slight decrease in the number of circulating platelets (usually not less than 100,000/ml); this form of thrombocytopenia is generally a benign , asymptomatic condition and tends to resolve itself within 2 months of delivery.
However, it should not be forgotten that there are various causes of thrombocytopenia during pregnancy, which can be both benign and mild, but sometimes even more marked and associated with severe pathological conditions for the health of the mother and the fetus (ii ) . The symptoms of the mother and the laboratory tests will be correctly evaluated by the attending physician to distinguish any pathological thrombocytopenia.
Values of blood clotting factors in pregnancy
A normal pregnancy is also associated with various alterations of the haemostatic system , i.e. the system responsible for stopping, through the procoagulant forces, the leakage of blood caused by a wound, but also to maintain adequate fluidity of the blood through the anticoagulant forces.
During pregnancy there is regularly an increase in procoagulant factors (fibrinogen, thrombin, von Willebrand factor antigen and various coagulation factors) and a concomitant reduction in some anticoagulant factors. It is believed that these changes may play an important role in reducing blood loss due to childbirth but, at the same time, increase the thrombotic risk during pregnancy (iii) .
The physiological anemia of pregnancy, due to haemodilution, partially plays a protective role against this thrombotic risk. The presence of additional risk factors for the onset of thrombosis, hereditary or acquired, will be adequately evaluated by your referring physician.
Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.
Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.