Personalized Risk Assessment and Early Detection — Let’s Plan Together to Protect Your Health
First Steps for Your Baby’s Health
Pregnancy is an exciting journey for expectant parents, but it can also bring moments of concern.
During this period, various screening tests are performed to monitor your baby’s healthy development and to identify potential risks early.
At our clinic, we closely follow both your health and your baby’s well-being through carefully planned screening programs conducted at different stages of pregnancy.
First Trimester Combined Screening (Weeks 11–14)
The First Trimester Combined Screening Test assesses the risk of chromosomal abnormalities such as Down syndrome (Trisomy 21) and consists of two main components:
- Ultrasound Examination: The baby’s nuchal translucency (NT) is measured. An increased NT thickness may be an early indicator of certain chromosomal abnormalities.
- Blood Test: A maternal blood sample is analyzed to measure levels of free beta-hCG and PAPP-A hormones.
By combining these two data points, the test estimates the likelihood of your baby having specific chromosomal anomalies.
This test is non-invasive and has an accuracy rate of approximately 85–90%.
Triple and Quadruple Screening Tests (Weeks 16–18)
If the first trimester screening was not performed or if additional evaluation is required, Triple or Quadruple Screening Tests can be done between the 16th and 18th weeks of pregnancy.
- Triple Test: Measures maternal blood levels of AFP, hCG, and estradiol (E3) to assess the risk of Down syndrome and neural tube defects.
- Quadruple Test: Includes the same three markers as the triple test, plus inhibin-A, which increases the accuracy of detection.
The quadruple test can detect about 75–80% of Down syndrome cases.
These tests estimate the risk of certain congenital anomalies but do not provide a definitive diagnosis. Additional diagnostic tests may be needed for confirmation.
Non-Invasive Prenatal Test (NIPT)
The NIPT can be performed as early as the 10th week of pregnancy. It analyzes fragments of fetal DNA circulating in the mother’s blood to assess the risk of chromosomal anomalies such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and Patau syndrome (Trisomy 13).
It is a highly accurate and non-invasive screening method.
Detailed Ultrasound Examination (Weeks 20–23)
Conducted between the 20th and 23rd weeks of pregnancy, this anatomical scan evaluates your baby’s overall development in detail.
It examines the baby’s organs, spine, skeletal structure, and brain and heart development, helping identify potential structural abnormalities at an early stage.
Interpreting Test Results
Prenatal screening tests estimate the risk of specific genetic or structural conditions but do not provide a diagnosis.
If a high-risk result is identified, diagnostic procedures such as amniocentesis or chorionic villus sampling (CVS) may be recommended.
At our clinic, all test results are thoroughly reviewed and explained to you in detail to ensure you feel informed and supported throughout your pregnancy journey.
Frequently Asked Questions
At What Measurement Is Nuchal Translucency Considered Abnormal?
The measured nuchal translucency (NT) value is interpreted according to gestational age. It is considered increased when it is above the 95th or 99th percentile for that specific gestational week.
Regardless of gestational age, an NT measurement of 3.5 mm or more is regarded as definitely increased. In general, the greater the NT thickness, the higher the likelihood of chromosomal or structural abnormalities.
Is Increased Nuchal Translucency Only Important for Chromosomal Abnormalities?
NT measurement between 11 and 14 weeks not only assesses chromosomal risks but may also indicate early fetal organ abnormalities, such as issues in the head, heart, stomach, kidneys, abdominal wall, spine, or skeletal system.
If no chromosomal anomaly is detected and a detailed ultrasound confirms that all fetal organs appear normal, and the NT returns to normal later in pregnancy, the outcome is generally favorable.
Long-term neurological follow-ups of such children have also shown good results.
When the fetus and maternal anatomy allow, advanced ultrasonography performed by specially trained physicians can identify more than half of possible fetal anomalies at an early stage.
| Nuchal Translucency | Chromosomal Abnormality | Fetal Death | Major Anomalies | Live & Healthy |
| < 95th percentile | 0.2% | 1.3% | 1.6% | 97% |
| 95–99th percentile | 3.7% | 1.3% | 2.5% | 93% |
| 3.5–4.4 mm | 21.1% | 2.7% | 10.0% | 70% |
| 4.5–5.4 mm | 33.3% | 3.4% | 18.5% | 50% |
| 5.5–6.4 mm | 50.5% | 10.1% | 24.2% | 30% |
| > 6.5 mm | 64.5% | 19.0% | 46.2% | 15% |
What Do the Blood Hormone Tests (Free β-hCG and PAPP-A) Indicate and How Are They Interpreted?
During pregnancy, β-hCG levels decrease as gestation progresses, while PAPP-A levels increase.
In Trisomy 21 (Down syndrome), β-hCG levels are elevated and PAPP-A levels are decreased.
These hormones are measured from a maternal blood sample and compared to population averages for that gestational week.
On their own, these hormone tests can identify about 40% of Down syndrome cases. When combined with nuchal translucency measurement, forming the Combined Screening Test, diagnostic accuracy increases to 80–85%.
Can the First-Trimester Combined Test Show Abnormal Results for Reasons Other Than Down Syndrome?
Yes. Abnormal results can also be observed in Trisomy 13, Trisomy 18, or Triploidy (69 chromosomes).
- In Trisomy 18, both PAPP-A and β-hCG levels are decreased.
- In Triploidy (paternal type), β-hCG is significantly increased, while PAPP-A is slightly reduced.
Recent studies show that a very low PAPP-A level (<0.4 MoM) is associated with preterm birth, growth restriction, intrauterine fetal loss, and preeclampsia.
Similarly, elevated β-hCG levels have been linked to a higher risk of adverse pregnancy outcomes.
What Is Toxoplasmosis?
Toxoplasmosis is an infection transmitted through undercooked meat or cat feces. It can also spread via unwashed fruits and vegetables or contaminated water.
If a woman contracts this infection during pregnancy, it can cause fetal abnormalities such as enlarged liver and spleen, hydrocephalus, or low birth weight.
Most women of reproductive age have already had toxoplasmosis and are immune, so the risk of new infection during pregnancy is very low.
Because the risk is minimal, many countries do not recommend routine toxoplasmosis screening during pregnancy.
How Can Pregnant Women Protect Themselves from Toxoplasmosis?
There is no vaccine for toxoplasmosis. Prevention includes:
- Cooking all meat thoroughly, avoiding raw or undercooked meat.
- Washing hands well after handling raw meat.
- Washing or peeling all fruits and vegetables.
- Avoiding areas contaminated with cat feces.
- Wearing gloves when cleaning cat litter boxes.
What Is CMV (Cytomegalovirus)?
CMV is a viral infection similar to the flu. If contracted during pregnancy, it may cause serious fetal complications.
However, in many countries, a large proportion of adults are already immune due to prior exposure to the virus.
Is Rubella (German Measles) Screening Necessary?
Rubella is typically a childhood infection transmitted via respiratory droplets.
About 95% of adults are immune because they have had the infection earlier in life.
Immunity can be checked through a simple blood test.
If a woman is not immune, vaccination before pregnancy is strongly recommended.
If rubella infection occurs early in pregnancy, it can cause serious heart, eye, and liver defects in the baby.
After vaccination, pregnancy should be avoided for at least one month, and the vaccine should not be given during pregnancy, as it contains a live virus.
Why Is Syphilis Screening Important During Pregnancy?
Syphilis can cause miscarriage, preterm birth, and neonatal jaundice, as well as enlarged liver and damage to the baby’s eyes, brain, and bones.
For this reason, testing for syphilis before pregnancy or early in pregnancy is essential.
High-risk groups include individuals with:
- Substance use disorders
- HIV infection
- Low socioeconomic conditions
- Multiple sexual partners
Why Is Hepatitis B Screening Recommended Before Pregnancy?
Approximately 10% of pregnant women are Hepatitis B carriers.
Although Hepatitis B does not typically harm the fetus during pregnancy, it can be transmitted to the baby during delivery.
If the mother is a carrier, the newborn should receive both the Hepatitis B vaccine and a protective immunoglobulin injection at birth.
Without this precaution, serious infections may develop in the child later in life.
Therefore, Hepatitis B screening is an essential part of preconception and prenatal care.
Additionally, if not previously done, thyroid hormone levels should also be checked before pregnancy, since untreated thyroid disorders can cause complications during gestation.
