PRENATAL & POSTNATAL DNA TESTS

WHAT TO DO TO AVOID MISCARRIAGES and HOW TO TAKE PREVANTATION in PREGNANCIES (PRENATAL TESTS)

 

The Process of Pregnancy

In the womb, life starts as one cell. This one cell turns into 100 trillion cells and 216 organs. The process of pregnancy includes 3 main trimesters. We name these trimesters as the trimester of formation, development, and growth. The first trimester is the trimester of formation. At that time, the baby is in the form of a clot. For that reason, clotting disorders are very important; both for the mother and the baby. The second trimester is the trimester of development. At that time, organs and the genetic structures that have passed from the mother and the father develop. The third and the last trimester is the trimester for the organs to grow. At that trimester, along with the genetic structure, environmental factors are also very important.

 

The Frequency of Miscarriage

The frequency of causeless miscarriage (i.e. miscarriage that occurs naturally in a healthy mother) is about 1%. The pregnancy that occurs after the miscarriage results in healthy birth in the rate of 60-70%. The risk of miscarriage increases with the number of miscarriages that has happened. The risk of miscarriage is:

  • about 15% after the first miscarriage,
  • about 24% after the second miscarriage,
  • about 30% after the third miscarriage
  • about 40-50% after the fourth miscarriage.

 

The age of the mother is an important factor that affects miscarriage. The risk of miscarriage starts to increase after the age of 25; it can even reach to 75-80% after the age of 45.

 

The Reasons of Miscarriage

1)    Unknown Causes

 

2)    Genetic Factors: Such diseases can be foetal or parental.

a)    Chromosomal Diseases:

    • Chromosomal abnormalities in foetus or miscarriage material: More than 80% of miscarriage cases occur in the first trimester and 53% of these occur due to chromosomal abnormalities. To detect these abnormalities; chromosomes in chorionic villus, amnion, and cord blood samples are analysed.
    • Chromosomal abnormalities in parents: In parents with a history of multiple miscarriages, the frequency of detection of chromosomal abnormalities is known to be about 3-10%.

 

b)    Single Gene Disorders: Women with a familial history of single gene disorders (such as cystic fibrosis, thalassemia, and sickle-cell anaemia) have a higher chance of miscarriage than healthy women. 

Familial history, physical examination, pathological analysis, and genetic research conducted on both parents and foetus are very important in the detection of single gene disorders. Detailed pedigree should be constructed, and genetic consultation should be given.

  

c)  Hereditary Thrombophilia: The incidence of thrombophilia in the families with multiple miscarriages can go up to 60%. Placental atherosclerosis that occur due to hereditary and/or gained thrombophilia-related disorders significantly increase the risk of multiple miscarriages and other complications.

 

The most frequently analysed genes that are related to thrombophilia are; Factor II (PTH) G20210A, Factor V G1691A, Factor V H1299R, Factor XIII V34L, MTHFR C677T, MTHFR A1298C, PAI-1 (4G/5G), EPCR A4600G (A3), and EPCR G4678C (A1).

 

3)    Endocrine Factors

4)    Autoimmune Factors

5)    Anatomical Factors

6)    Infections

 

Prevention of Miscarriage

For better analysis, all the tests for thrombophilia and chromosomal analysis should be applied to both parents. Genetic consultancy is given according to the results. For example, if both parents are carriers; the foetus has 25% chance of being sick, 50% chance of being a carrier, and 25% chance of being healthy. All the genes that are related to miscarriage should be analysed this way. Then, proper medication and dosage should be prescribed to the mother during pregnancy.

 

Pregnant women with hereditary thrombophilia may develop miscarriage, intrauterine foetal death, severe preeclampsia, and intrauterine developmental disorders. If such women must take a flight longer than 4 hours; elastic compression socks, hydration, physical activities, and medication are recommended.

 

Folic acid, aspirin, and low molecular weight heparin (LMWH) have been found to be effective in the prevention of miscarriage.

 

The dosage of the medication should be determined according to the genetic structure of the mother and the foetus. Proper consultation from an ob/gyn specialist, genetics specialist, and haematology specialist should be taken. If necessary, the pregnancy must proceed under control of all these specialists.

 

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