11th-14th week

 

Visit includes screening for the possibility that the fetus has one of the most common chromosomal abnormality called Down's syndrome. The chances of a fetus having Down's syndrome depend on factors such as hereditary predisposition from the parents, the increased maternal age and also a random event.

Hereditary predisposition is checked through the history of the parents, i.e. if there was a member with Down syndrome in two families of the future parents or if another child with this syndrome was born from the same parents.

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It is also proven that as the mother's age increases, the probability of having a child with Down syndrome increases. Especially after the age of 35 the risk doubles sharply compared to younger women.

The check includes:

1.  Ultrasound in which the age of the fetus is calculated very accurately, based on the measurements, and also the Nuchal Translucency (of the fetus), the most important ultrasound indicator for calculating the risk for Down's syndrome.

2. Blood test where the levels of two important elements of pregnancy are calculated, the pregnancy hormone  called β-chorionic gonadotropin (β-hCG) and protein PAPP-A.

3. The combination of the above three parameters gives us, through a statistical program, the probability of having a child with Down's syndrome, with reliability close to 90%. Of course, in order to have a 100% result regarding the existence of chromosomal abnormalities, the recommended method is amniocentesis, the reception and analysis of amniotic fluid.

It should be emphasized that screening for chromosomal abnormalities is offered to all couples and is part of standard screening during pregnancy.

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Trophoblast biopsy

Technique with which we can accurately determine the chromosomes of the fetus (karyotype). With a thin special aspiration needle, it is guided from the abdominal skin to the placenta of the fetus, with continuous ultrasound monitoring, and cells from the placenta and amniotic fluid are aspirated. Then the material is sent for analysis.  The technique shows greater specificity in investigating the presence of homozygous β-mediterranean anemia or sickle cell anemia in fetuses with parents who both have the "stigma"/trait of one of the two types anemias. All types of chromosomal abnormalities are diagnosed with the same technique, but it is not offered to all couples since the risk of miscarriage is very small (<1%) but not non-existent. The method is applied in special prenatal control centers by specialized doctors. The appropriate gestational age for trophoblast biopsy is considered to be 12-13 weeks.