What blood tests during pregnancy?

First pregnancy blood test: the one that confirms that you are pregnant!

Faced with a late period or pregnancy symptoms, the first instinct of women is to run and buy a urine test at a pharmacy. Easy to use, it gives a quick result but not as reliable as a blood test. If the urine test is positive, your doctor or gynecologist will order a blood test to confirm pregnancy. You can also go to a laboratory without going through the doctor’s box, so without a prescription (but you will not be reimbursed by Health Insurance).
This first blood test measures your level of human chorionic gonadotropic hormone, better known as beta-HCG. This hormone is present in a woman’s body only during pregnancy. It is produced shortly after conception, when the egg is implanted in the uterine lining and then by the placenta. Its level increases rapidly at the beginning of pregnancy and then decreases until term. It is detectable from the 10th day after ovulation if there has been fertilization. In the event of pregnancy, the level of HCG is higher than 8IU / L of blood at the implantation stage and doubles every 48 hours. A peak is observed between the 2nd and the 3rd month of pregnancy then falls and then decreases until the baby arrives. To know the dosage of HCG according to the age of pregnancy, see our article.

Screening for Down’s syndrome

During the first trimester of pregnancy, more precisely between the 11th and the 13th week of amenorrhea (SA), a blood test is offered to the pregnant woman to assay the serum markers. These substances are secreted by the placenta or the fetus and are found in the maternal blood. A lower or higher rate than the average can be the sign of a trisomy 21. The result of this blood test (after ten days) makes it possible to establish a probability that the fetus has a trisomy 21 .

Determining the blood group

If it is not already known, the blood type of the pregnant woman is determined at the onset of the first pregnancy. This test can detect a problem of rhesus incompatibility if the mother-to-be has a rhesus negative blood group and the fetus’ blood group is rhesus positive. This incompatibility can have serious consequences on the fetus during a possible second pregnancy if it is rhesus positive (the body produces irregular agglutinins, antibodies that are dangerous for the fetus). This is why rh negative women receive an injection of anti-rh serum after each delivery to protect the future baby (s). Women whose pregnancy ends in miscarriage or termination of pregnancy (abortion or IMG) also receive this injection.
Knowledge of the blood group of the mother-to-be by the health professionals who will take care of her during childbirth is also essential in the event of significant bleeding requiring a transfusion.

Screening for rubella and toxoplasmosis

Rubella and toxoplasmosis are two diseases that can be dangerous for the fetus, especially if they are contracted during the first trimester of pregnancy. The only way to know if you are immune is to have a blood test. This test measures the level of antibodies to effectively fight the disease in case of infection. Screening for toxoplasmosis is mandatory in pregnant women. If the test is positive, it means that the patient is protected because she has already contracted the disease. If the test is negative, she will need to be tested for toxoplasmosis every month to check that she has not contracted the disease. A prescription will be issued to him every month by his doctor, his gynecologist or his midwife. Rubella screening is also one of the mandatory examinations during pregnancy. It is usually prescribed during the first prenatal visit, unless there is an old blood test showing immunity. If the pregnant woman is not immunized, it is strongly recommended to have another screening blood test during the first four months of pregnancy.

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Blood count formula (CBC)

This blood test can detect anemia in pregnant women. It is routinely prescribed during the 6th month of pregnancy because anemia increases the risk of premature delivery and maternal postpartum infections. Depending on the results, the healthcare professional following the pregnancy may prescribe an iron supplement.

Hepatitis B screening

Testing for HBs antigen is mandatory during the 6th month of pregnancy. If the expectant mother is infected with the hepatitis B virus during pregnancy, the risk of transmitting it to the child is high and the newborn can become a chronic carrier. In the event of negative serology, there is no risk for the unborn baby.

Screening for HIV and syphilis

HIV testing is not compulsory but strongly recommended by doctors. A pregnant woman who contracts HIV during pregnancy has a 1 in 4 risk of passing it on to the baby. If treated, this risk drops to about 1 in 100. If the result is positive, treatment is put in place to prevent mother-to-child transmission and improve the health of the mother-to-be.
Screening for syphilis is mandatory in pregnant women, ideally during the first three months of pregnancy. The examination is repeated during the 3rd trimester in women at risk (those having unprotected sex with a new partner after the first screening and those whose partner is infected).

Screening for gestational diabetes

If the pregnant woman has one or more of the risk factors for gestational diabetes, a blood glucose test is recommended. These are two exams:

• first trimester fasting blood sugar.
• and / or the measurement of glycemia during hyperglycemia caused by the oral route between the 24th and 28th week of amenorrhea.

Annabelle iglesias

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