Blood tests in pregnancy

Blood tests in pregnancy
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Blood tests in pregnancy

You just found out you are pregnant and your gynecologist has told you that you will do a series of blood tests during the nine months, to monitor your and baby's health. What exams? What are they for? How often should they be repeated, if they should be repeated? Are they also used to identify fetal malformations?
"For each trimester of pregnancy there are some blood tests required by the Lea guidelines (the Essential Levels of Assistance)" says Giulia Ferri, gynecologist at the Sant'Anna hospital in Como. Exams that, if carried out in public - or private but affiliated with the NHS - and in the weeks of pregnancy provided, are free. On the basis of the results of certain tests, the gynecologist will then evaluate whether it is necessary to repeat them during the pregnancy or to prescribe further investigations ".





In this article

Read also: Preconception examinations: what they are

Blood tests of the first trimester of pregnancy

The examinations in the first trimester are of general classification, that is, they are used to assess the initial health situation in which the woman finds herself. These are tests that generally begin to be done once the pregnancy is ascertained, unless they have already been performed in the preconception period, for example if the couple has followed a path of medically assisted procreation. Here's what they are.



Blood group and Coombs test

It is important to know your blood type and in particular it is important to know if the expectant mother has a positive or negative Rh factor. "If the woman has a positive Rh, at the beginning of pregnancy and then at 28 weeks another test called indirect Coombs test is done", comments the gynecologist; "if, on the other hand, the future mother is Rh negative, while the partner is Rh positive, the test must be repeated on a monthly basis until the end of pregnancy. This is in order to check whether the mother is producing antibodies against the positive Rh factor of the fetus; antibodies that they could be harmful to the baby or to future pregnancies. "
It is a free exam.

Basal blood glucose

It is used to measure the blood sugar level. It is measured in the first trimester, after which, if the values ​​are altered or if the woman has risk factors, the gynecologist decides whether to prescribe a glycemic load curve between the 16th and 18th week or between the 24th and 28th week.
If, on the other hand, the values ​​are normal and there are no risk factors, the blood sugar is measured only in the first trimester, after which it is evaluated case by case whether to repeat it later, also based on how much the mother gains weight or how much the child grows. .
It is a free exam.

Rubeo test and toxo test

They are prescribed to check whether the woman has already contracted rubella and toxoplasmosis, which, if caught during pregnancy, can pose a risk to fetal health. The test for rubella is not needed if the woman was vaccinated before pregnancy; for toxoplasmosis, on the other hand, there is no vaccine, so the examination must be done. 
It is a free exam.



Test for cytomegalovirus

Cytomegalovirus is a viral infection which, if contracted during pregnancy, can cause serious health problems for the unborn child. "On the other hand, the probabilities that the infection will pass to the fetus causing consequences are quite low, so there is no universal consensus on the advisability of prescribing the routine test" observes Giulia Ferri. "If the gynecologist deems it appropriate, it is usually done early in the pregnancy and then around the 20th week".
It is not foreseen in the Lea, so there is a ticket to pay which is around 10 euros.

Hemoglobin electrophoresis

It is used to evaluate if there are abnormal variants in hemoglobin and therefore to identify if you are a carrier of thalassemia, i.e. Mediterranean anemia. "In Del Paese, thalassemia is more widespread than you might think, because you are often a carrier but have no symptoms, so you don't even know you have it" says Giulia Ferri. "It must be verified because, if the mother is a carrier, the father must also be analyzed: if he too is a carrier, there is a high risk of transmitting thalassemia maior, which is the symptomatic form, to the fetus, and at that point the gynecologist will prescribe more in-depth checks. If, on the other hand, the values ​​of the mother are within the norm, there is no need to make any additional checks, not even to the father ".

Hemoglobin electrophoresis falls under the Lea, so it is free of cost.

Complete blood count

It is done to measure the concentration of red blood cells in the blood and diagnose any anemia. It is done in the first trimester to see what the starting values ​​are, after which it is repeated at the end of pregnancy to assess whether there are the 'right supplies' for the birth.
The values ​​that are of most interest from a medical point of view are hemoglobin, which is the main component of red blood cells and serves to transport oxygen to various tissues, and platelets, which can signal coagulation disorders, to be known especially in view of childbirth. and a possible recourse to analgesia childbirth.
Made in the times foreseen by the Lea, it is free.

Test for HIV and syphilis

Both are infectious disease tests: the syphilis test is usually done only once (except for particular social situations), between the first trimester tests; that for HIV is done in the first trimester and then is repeated in the third trimester.
They are both exams charged to the NHS.

Test for Hepatitis B and C

Screening for both types of hepatitis is done routinely in the first trimester.
They are exams foreseen by Lea.

The doctor may then order a fibrinogen test if there is a risk of placental abruption or clotting problems.

Blood tests of the second trimester of pregnancy

Glucose load curve

It is a test that can be prescribed by the gynecologist if the woman is assessed to be at risk of developing gestational diabetes. The examination is carried out in 3 phases: first the basal blood sugar is measured in fasting for at least 8 hours, then the woman is made to drink a sweet syrup containing 75 g of glucose and two more samples are taken, the first at a distance of 1 now, the second after 2 hours. 
The glycemic curve can be done at 16-18 weeks or at 24-28 weeks.

"The glycemic curve at 16-18 weeks is prescribed if one of these defined major risk factors is present" explains the gynecologist:

  •  if the woman had gestational diabetes in a previous pregnancy;
  •  if it is an obese lady, that is, with a BMI greater than or equal to 30 at the beginning of pregnancy;
  •  if the baseline blood glucose values ​​measured in the first trimester were between 100 and 125 ".

If the woman has risk factors, the load curve is one of the free tests.

Rubeo test out toxotest

According to the Leah, if the woman tested negative in the first trimester and therefore never contracted rubella and toxoplasmosis, both tests should be repeated approximately every month-month and a half, because, if contracted during pregnancy, certain diseases can cause lead to major fetal malformations.
Toxoplasmosis in particular must be repeated until the end of pregnancy, while the rubella examination is enough to repeat it up to the 20th week, because it has been seen that, if contracted later, it does not cause problems.  

Cytomegalovirus

If the first trimester test is negative, it is repeated around the 20th week, even if not all gynecologists consider it appropriate.

Indirect Coombs test

If the woman is Rh negative, while the partner is Rh positive, the test is repeated monthly, until the end of the pregnancy.

Blood tests of the third trimester of pregnancy

Glucose load curve

It can be prescribed between the 24th and 28th week of pregnancy if the woman does not have the major risk factors (which would have required an early curve at 16-18 weeks), but still has the following risk factors, defined as minor:

  •  if the woman is over or equal to 35 years of age;
  •  if you are overweight, with a BMI greater than or equal to 25;
  •  if you had gestational diabetes in a previous pregnancy, but the glycemic curve made at 16-18 was negative;
  •  if in the previous pregnancy you had a macrosomal baby, that is, weighed more than 4,5 kg at birth (often in fact the macrosomia is due to an intolerance to glucose that had not been identified);
  •  if there are first degree relatives (mom, dad, brother) already suffering from type 2 diabetes.

If the woman has risk factors, the load curve is one of the free tests.

Toxo test

It is carried out monthly until the end of pregnancy.

Complete blood count

If the blood counts of the first trimester were normal, it is repeated in any case in the third trimester to evaluate the situation in view of delivery.

Test for HIV and syphilis

HIV is repeated routinely in the third trimester; syphilis does not, unless there are particular risk factors.

Test for Hepatitis B and C

The test for hepatitis B is repeated in the last trimester because, if the mother is positive, the newborn is given immunoglobulins in the first 72 hours of life, to protect him from a possible infection.
The hepatitis C test is not repeated unless there are particular risk factors.

Indirect Coombs test

It is repeated to all women in the 28th week. If the woman is Rh negative, while the partner is Rh positive, the test is repeated monthly, until the end of the pregnancy.

Exams eliminated by Lea

In the past, transaminases and creatinine were among the scheduled routine examinations in pregnancy: both were removed from the last Lea released in 2022. "They were once inserted to have a basic early pregnancy picture of liver and kidney function; in reality it has been seen that, if the woman has a negative anamnesis, that is, she does not suffer from any pathology, it is useless to measure them "underlines the gynecologist. "On the other hand, it makes sense to monitor certain values ​​if the woman develops pregnancy pathologies, such as gestational hypertension or preeclampsia, or if there is a reduction in fetal growth, with the risk of undergoing placental pathologies that compromise liver and kidney function". 

Can you eat before blood tests?

"It depends on the tests" replies Ferri: "if the mother has to measure the basal blood sugar or has to undergo a glycemic load curve, she must fast for at least 8 hours; for infectious tests, such as toxoplasmosis or rubella, there is no it is necessary; for the blood count you can have a light breakfast ".

Can you tell if you are pregnant with normal blood tests?

"No, it is necessary to look for the pregnancy hormone, which is Beta hCG" replies Giulia Ferri: "however, the dosage in the blood of this hormone is not routinely recommended, because when a pregnancy is assumed, it is sufficient to do a urine test, since the same hormone is also secreted there. To date, Beta hCG are prescribed by the doctor only in selected cases, for example if an ectopic pregnancy is suspected. Or if the pregnancy comes from MAP, to have a better result early".

Read also: Exams in pregnancy

Blood tests to detect malformations

There are blood tests that are not diagnostic tests, that is, they do not give a certain diagnosis (such as CVS and amniocentesis), but they are screening tests, that is, they indicate a percentage of risk that the fetus may be affected by chromosomal pathology.

The combined test of the first trimester or duo-test

It is a test consisting of two types of exams. The first is a blood test that is done between the ninth and eleventh week, with which two proteins of placental origin are measured, Papp-a and Free-beta hCG, which, as we have seen, in the case of a fetus aneuploid (ie suffering from chromosomal disease) have different values ​​compared to pregnancy with euploid, ie healthy, fetus. The value of this examination is integrated with an ultrasound, known as the nuchal translucency, which is done between the 11th and 13th week, with which some ultrasound markers of risk of chromosomal pathologies are assessed. By analyzing the two tests together, we calculate the risk that that pregnancy has a fetus with chromosomal pathology or not.
The ultrasound of the nuchal translucency is free, the blood test requires a ticket of about 50 euros.

Fetal DNA test

It involves a blood sample around the tenth week of gestation: it has in fact been seen that starting from this gestational period the trophoblast cells (which will give rise to the placenta) release the DNA of the fetus into the maternal circulation which, with particular genomic techniques, they can be detected in the mother's blood starting from the 10th week. It is still a screening test but has a much higher sensitivity than the duo-test, above 99%, compared to about 96% for the combined test.  
The DNA test is not yet reimbursed by the NHS: it is done only in private laboratories and costs around 4-500 euros. 

Also read: Urine tests in pregnancy

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