Blood tests in pregnancy: why are they performed in each trimester3 min read
Blood tests are an important part of prenatal checkups. It is a simple procedure that consists of extracting a blood sample from the pregnant woman and provides valuable information about her state of health.
An analysis is usually carried out per trimester and each of them is key at that time of pregnancy to prevent possible complications or make decisions about treatments to follow, therefore it is important not to skip any. We tell you in depth why blood tests are performed during pregnancy .
First quarter analytics
In the first control of the pregnancy, the doctor will request a normal blood test that includes information on the presence or absence of antibodies or possible infections that the mother could pass to the fetus through the placenta.
The first analysis serves to know:
- Blood group and Rh factor : It is necessary to know if the mother is Rh negative and there could be Rh incompatibility with the fetus in order to prevent complications or determine the treatment to follow.
- Hemogram and platelets : measures the number of red and white blood cells and platelets and is used to detect anemia or infectious processes.
- Glycemia : measures the concentration of glucose (sugar) in the blood and is used to determine the possible appearance of gestational diabetes , a disease that disappears after childbirth, but which, if not controlled, can cause serious complications in pregnancy.
- Hepatitis B and C : determines if the pregnant woman is a carrier of the hepatitis B or C virus. All pregnant women should be tested, preferably in the first trimester to take the necessary measures if the result is positive.
- Syphilis antibodies (luetic serology) : this is a test called RPR or VDRL that rules out the presence of syphilis antibodies, an infection that can cause serious consequences in the fetus and should be prevented from being transmitted.
- Toxoplasmosis antibodies (IgM) : most adults have already suffered from it, almost all without symptoms, but during pregnancy it can seriously affect the fetus, and even cause a miscarriage. If the pregnant woman has had the disease, she has defenses against it, but if she has not, the doctor will recommend a series of measures to avoid the risk of infection .
- Rubella antibodies : Most women have been vaccinated, but if you catch the disease during pregnancy it can cause serious harm to the fetus. If the woman is not vaccinated (she cannot receive it during pregnancy), it is recommended to avoid any risk situation.
- HIV antibodies (AIDS) : if the virus is diagnosed in the mother, early action can be taken to reduce the risk of transmission to the fetus.
- Indirect Coombs test : performed on all pregnant women to detect the presence of anti-HR antibodies.
- Triple screening or biochemical screening : in triple screening , three enzymes of the fetus present in the mother’s blood (BHGC, estriol and alpha-fetoprotein) are measured to determine the risk of chromosomal abnormalities in the fetus such as Down Syndrome, Edwards Syndrome and birth defects. neural tube. It is assessed with the results of the ultrasound performed at week 12 of pregnancy .
Second quarter analytics
- Complete blood count : The number of red blood cells and the hemoglobin and hematocrit values are again checked to monitor the mother’s anemia status. Physiological anemia usually occurs in pregnancy , but if it were accentuated it could affect the baby’s well-being as it would decrease the supply of oxygen through the blood.
- O’Sullivan test (sugar curve) : it is performed to detect gestational diabetes through the administration of a 50 g glucose solution. It’s not necessary to skip breakfast.
- Toxoplasmosis antibodies : if the first test determines that the woman does not have antibodies against the disease, it is done again to rule out that she has contracted it.
- Indirect Coombs test : Allows detecting the presence of antibodies related to hemolytic disease .
Blood test in the third trimester
- Hemogram : it is performed again to assess the presence and degree of anemia.
- Coagulation tests : it is carried out before delivery to assess the risk of hemorrhage at the time of delivery and the impossibility of applying epidural anesthesia.