- ATHENS OFFICE MED4WOMAN ATHENS
- VOLOS OFFICE MED4WOMAN VOLOS
Obstetrician-Gynecologist
PhD, University of Athens Medical School
Obstetrician-gynecologist Panagiotis Polyzos practices at the Institute of Life, the IVF Unit of IASO Maternity Hospital.
Prenatal screening consists of a series of tests designed to ensure the good health of both the mother and the baby. Many women believe it only refers to blood tests performed early in pregnancy to assess the mother’s health and her ability to safely carry the pregnancy to term. While these tests are indeed very important, equally essential are those that focus on the fetus, carried out through biochemical analyses and ultrasound imaging throughout the course of the pregnancy.
It begins with a positive pregnancy test, or even before a couple starts trying to conceive, and continues throughout the entire pregnancy.
Prenatal screening plays a pivotal role in pregnancy. Firstly, the expectant mother undergoes basic testing for certain conditions that can and should be treated in advance. Additionally, issues may arise during pregnancy that could pose risks to the health of both the fetus and the mother, many of which can be effectively managed when detected early. In every case, prenatal screening provides the mother with valuable information about her baby’s condition before birth, always within the limits of what can be determined.
It is, and it is highly important. Certain conditions that require special care are taken into consideration, such as:
The complete set of examinations includes:
Both procedures allow chromosomal testing of the fetus, and depending on the condition being investigated, may include genetic and enzymatic analysis.
Amniocentesis is the oldest method of obtaining fetal cells. The test is performed after the 16th week of pregnancy and up until the end of gestation, though more commonly up to the 22nd week. The amniotic fluid is collected using a fine needle inserted through the mother’s abdomen under continuous ultrasound guidance. The entire procedure is almost painless and completed within seconds. There is a small yet measurable risk of miscarriage, while the risk of injury to the fetus, as well as to the mother, is essentially negligible.
Chorionic Villus Sampling (CVS) is performed from the 12th week of pregnancy onwards, also under continuous ultrasound monitoring and using a very fine needle. Both amniocentesis and CVS carry the same risk of miscarriage. The advantage of CVS is that it can be carried out earlier than amniocentesis; however, its drawback is that it is not always feasible due to anatomical factors (such as uterine position, placental location, or maternal body habitus).
There is now also non-invasive prenatal testing or screening (NIPT/NIPS). This method analyzes fetal DNA circulating in the mother’s bloodstream to determine, with high accuracy, the risk of the fetus having Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), and numerical abnormalities of the sex chromosomes (X and Y). The test is performed through a simple maternal blood draw. The sample is sent to a specialized laboratory in the United States. NIPT is performed in singleton pregnancies beyond 9 weeks and carries no miscarriage risk.
In almost all cases where the diagnosis is made by a certified laboratory, the baby will be born healthy. However, certain syndromes caused by microdeletions (e.g., Williams syndrome, Prader-Willi/Angelman syndrome, DiGeorge syndrome, etc.) are not visible under a microscope and can only be detected using specialized molecular methods such as MLPA and array-CGH. It is important to highlight that even with a normal result from the recommended prenatal testing, this should not be interpreted by parents as a guarantee that the baby will be free from all medical conditions. For example, a normal fetal karyotype ensures that the baby does not have congenital abnormalities caused by a chromosomal syndrome, but it does not rule out all possible genetic disorders or congenital anomalies of other origins.
Prenatal testing is not a single test but a journey. The schedule below shows the usual order in an uncomplicated pregnancy. Your doctor may adjust it based on your history.
Prenatal tests for the fetus fall into two categories, and confusing them causes a lot of anxiety.
The approach is stepwise. All women have screening. Only a small percentage end up needing a diagnostic test. This way, not everyone undergoes an invasive procedure, while the fetuses that need investigation are not missed.
Many of the factors that shape the outcome of a pregnancy can be addressed before it even begins. A preconception visit, ideally three months before you start trying, includes:
You will find more practical guidance for this stage in the article on how to get pregnant.
After the anatomy scan, many women assume testing is complete. The last trimester, however, has its own tests:
The standard schedule covers most women. Some situations, however, call for additional tests or closer monitoring:
Bring all your past medical records to the first appointment. A complete history is the cheapest and perhaps the most useful part of prenatal testing.
A child can be born with a recessive genetic disease even if no one in the family has it. It is enough for both parents to be healthy carriers of the same gene. In that case, the chance in each pregnancy is one in four.
In Greece, testing for thalassemia and sickle cell disease is standard. Many centers now also offer testing for cystic fibrosis and spinal muscular atrophy, as international guidelines recommend, while women with a family history of intellectual disability are also tested for fragile X syndrome. There are also expanded panels that check hundreds of genes at once.
Blood tests, blood type, infection screening, nuchal translucency scan with PAPP-A and beta-hCG and, optionally, NIPT.
A maternal blood test that analyzes cell-free fetal DNA and checks with high accuracy for the most common trisomies. It is a screening test, not a diagnostic one.
Nuchal translucency at 11 to 14 weeks, a level II (anatomy) scan at 20 to 24 weeks and a growth ultrasound with Doppler at 30 to 34 weeks.
Between the 24th and 28th week.
Yes, in Greece both parents are tested, ideally before conception or early in pregnancy.
Some, yes, such as the complete blood count, infection screening where there is no immunity, and the glucose tolerance test. Others do not need to be repeated, such as blood type and thalassemia carrier testing, as long as you have the old results.
It means you have not had the infection and could catch it during pregnancy. Avoid raw or undercooked meat, wash vegetables and fruit well, wear gloves when gardening and do not clean the cat's litter box. Your doctor may repeat the test during pregnancy.
Inactivated vaccines, such as the flu and whooping cough vaccines, are considered safe and also protect the newborn. Live vaccines, such as rubella and chickenpox, are not given during pregnancy and are done before conception or after delivery.
