Everything You Need to Know About Prenatal Tests and the Role of NIPT in Genetic Screening

The moment a woman discovers she’s pregnant, a mother is born.
A mother who dreams, who protects, whose heart races with every ultrasound, and who, above all, hopes her baby arrives in the world healthy. At this moment, when love blossoms in the womb, care takes center stage — and prenatal tests become essential allies on this journey.

Love is revealed in care, in choosing the right medical follow-up, and in opting for tests that provide safety and peace of mind for both the mother and the baby.

In this article, we explain the main tests performed in each trimester of pregnancy, with a special focus on NIPT — a non-invasive genetic test that allows early detection of chromosomal abnormalities. Keep reading to understand how laboratory medicine can transform prenatal care.

What Are Prenatal Tests and Why Are They Important?

Prenatal care involves various preventive, diagnostic, therapeutic, and health-promoting actions aimed at ensuring a safe and healthy pregnancy for both the mother and the baby (1).

During pregnancy, every choice matters — nutrition, rest, medical follow-up, and of course, prenatal testing. These tests are more than clinical protocols; they are tools to monitor the baby’s development and anticipate any special care needs.

Prenatal tests are part of routine medical follow-up aimed at safeguarding the health of the pregnant woman and her baby throughout the pregnancy (2). They enable the early identification of conditions that could interfere with fetal development, as well as prevent or treat issues that may arise during pregnancy, such as infections, gestational diabetes, and hypertension (3).

In addition, genetic and imaging tests help detect chromosomal abnormalities or fetal malformations, giving families the chance to properly prepare for delivery and postnatal care.

Among these tests, one has gained prominence for providing early, safe, and non-invasive genetic insights: NIPT (Non-Invasive Prenatal Testing).

What Tests Are Performed During Pregnancy?

The main prenatal tests include (4):

First Trimester (up to 13 weeks):

• Ultrasound: to check gestational age and sac location
• Blood tests: complete blood count, fasting glucose, serologies (HIV, syphilis, toxoplasmosis, hepatitis B and C), TSH, and free T4
• Blood typing and Rh factor
• Basic genetic tests (in some cases: nuchal translucency screening, NIPT)

Second Trimester (14-27 weeks):

• Morphological ultrasound: to assess fetal anatomy
• Glucose tolerance test (GTT): to detect gestational diabetes
• Follow-up serologies and urine tests (urine culture)
• Monitoring of blood pressure and weight

Third Trimester (28 weeks onward):

• Fetal well-being assessment: additional ultrasounds, cardiotocography, biophysical profile
• Repeat blood and urine tests
• Group B Streptococcus test (between 35 and 37 weeks)

Prenatal tests help identify silent conditions early, such as hypertension, diabetes, heart diseases, anemia, and infections — enabling timely treatment and preventing short- and long-term maternal complications. They also allow for the detection of fetal malformations, some of which can be corrected in utero, and evaluation of the placenta, whose improper placement can pose a serious hemorrhagic risk (3).

Prenatal monitoring is also critical for the early diagnosis of preeclampsia, a serious and potentially fatal condition characterized by high blood pressure and organ dysfunction.

What Is NIPT?

The Non-Invasive Prenatal Test (NIPT) is a screening exam that analyzes circulating cell-free fetal DNA (cfDNA) found in the mother’s blood. Performed from the 10th week of pregnancy, the test is simple, safe and non-invasive, requiring only a blood draw from the pregnant woman (5).

The main goal of NIPT is to identify early chromosomal abnormalities in the fetus, such as trisomies of chromosomes 21 (Down syndrome), 18 (Edwards syndrome), and 13 (Patau syndrome). Due to its high sensitivity, NIPT has become a safer alternative to invasive methods like amniocentesis and chorionic villus sampling — procedures associated with risks such as miscarriage (6).

Since the discovery of cfDNA in maternal plasma in 1997, prenatal diagnostics have undergone a revolution. Today, millions of pregnant women worldwide undergo NIPT as part of routine prenatal care (7).

Why Is NIPT a Milestone in Prenatal Care?

The introduction of NIPT into clinical practice marks a significant breakthrough in fetal medicine. As a non-invasive genomic screening tool performed early in pregnancy, it aids in anticipating potential risks and directing pregnancy monitoring more accurately.

The screening of aneuploidies such as trisomies 21, 18, and 13, from a simple maternal blood draw, enables clinicians and laboratory professionals to provide highly valuable clinical information — enhancing care planning with greater precision and safety.

This type of testing strengthens communication among all parties involved in maternal-fetal care, promoting a more personalized, evidence-based, and patient-centered approach.

It is important to note that NIPT is a screening, not a diagnostic test. Its role is to estimate the risk of specific chromosomal abnormalities, and its results must always be interpreted in the clinical context of the pregnant woman, along with other laboratory and imaging findings.

As a complementary tool, NIPT integrates into a broader preventive medicine strategy, supporting early decision-making, genetic counseling, and health team preparation for possible therapeutic interventions.

When Are Genetic Tests Recommended During Pregnancy?

Genetic tests during pregnancy can be recommended for all women, regardless of age or known risk factors. However, they are particularly indicated when there is:

• Advanced maternal age (over 35 years)
• Family history of genetic conditions
• Abnormal imaging findings (e.g., increased nuchal translucency)
• Positive or inconclusive biochemical screening results
• Parental desire for more accurate information on the baby’s genetic health

These tests help identify not only autosomal aneuploidies (chromosomal number abnormalities) but also changes in sex chromosomes — such as Turner and Klinefelter syndromes. They can also determine fetal sex and screen for other genetic syndromes. Expanded panels allow for the detection of microdeletions and other small genomic changes associated with specific syndromes, when clinically indicated. As such, genetic tests provide valuable information for both medical and family decision-making (8).

It is important to emphasize that any result obtained should be interpreted with caution and always discussed with the requesting physician, who can contextualize the findings based on the pregnant woman’s clinical and family history.

What types of non-invasive prenatal tests does SYNLAB offer?

SYNLAB offers two types of non-invasive prenatal tests (NIPT), both using cutting-edge technology for fetal genetic screening from a maternal blood sample.

neoBona

The neoBona test aims to identify genetic alterations such as:

• Trisomy of chromosome 21 (Down syndrome);
• Trisomy of chromosome 18 (Edwards syndrome);
• Trisomy of chromosome 13 (Patau syndrome);
• Sex chromosome aneuploidies (X and Y);
• Optional fetal sex determination.

This test employs whole genome sequencing (WGS Paired-end) technology combined with the analysis of the fetal fraction in maternal blood. It is indicated for both singleton and twin pregnancies.

neoBona Genomewide

The neoBona Genomewide provides an even broader assessment, and we have already explained in our blog how this non-invasive test works. In addition to the conditions detected by the neoBona test, it also allows for:

• Detection of aneuploidies in all autosomal chromosomes;
• Identification of copy number variations (CNVs) greater than 7 Mb;
• Fetal sex determination;
• Analysis of sex chromosomes.

This test is also based on WGS (Whole Genome Sequencing) Paired-end technology and the percentage of fetal fraction and is suitable for both singleton and multiple pregnancies.

How do SYNLAB’s neoBona tests work?

The procedure is simple: from the 10th week of pregnancy (10 weeks + 0 days), a small amount of the pregnant woman’s blood is collected in a specific tube provided in the kit by SYNLAB. Before this period, the amount of circulating fetal DNA (fetal fraction) is usually insufficient for reliable analysis.

During laboratory analysis, fragments of cell-free fetal DNA (cfDNA) present in maternal blood are sequenced. Then, the proportion of fragments from each chromosome is compared to reference patterns using a specialized bioinformatics algorithm.

The results obtained from cfDNA represent genetic screening, not a definitive diagnosis. Therefore, any finding suggestive of aneuploidy must be confirmed by invasive procedures such as amniocentesis or chorionic villus sampling, along with genetic counseling.

Who are neoBona tests recommended for?

For all pregnant women from 10 complete weeks of gestation (≥10+0/7), including the following situations:

• Singleton or twin pregnancies;
• IVF pregnancies;
• Gamete donation;
• Vanishing twin pregnancies.

Myths and facts about prenatal testing

During pregnancy, it is common to have doubts and even concerns about the tests that accompany prenatal care. Unfortunately, many myths circulate and can lead to misinformation or even neglect of one’s own health and the baby’s. Among the main myths, we can mention:

• I only need to take tests if I have symptoms

Most conditions that can affect pregnancy—such as gestational hypertension, gestational diabetes mellitus, infections, or chromosomal abnormalities—are asymptomatic in the early stages. Therefore, laboratory and imaging tests are preventive, allowing early identification of situations that can be treated or monitored before they cause complications for the mother or baby (9).

• NIPT is an invasive test

The Non-Invasive Prenatal Test (NIPT) is performed using a simple maternal blood sample, with no risk to the baby. The analysis is based on cell-free fetal DNA (cfDNA) circulating in the mother’s blood, allowing highly sensitive and specific screening for conditions such as trisomies of chromosomes 13, 18, and 21 (10).

• Genetic tests are only indicated for women over 35

Although advanced maternal age increases the risk of chromosomal abnormalities, tests such as NIPT can be indicated for pregnant women of any age—especially when there is a family history, suggestive ultrasound findings, or parental anxiety regarding fetal health (10).

• Taking many tests can harm the baby

Routine prenatal tests—such as blood and urine tests, ultrasounds, infectious disease screenings, and genetic screenings—are safe for the baby and essential for ensuring a healthy pregnancy. Even more frequent tests, such as ultrasound, pose no proven risk when performed appropriately and with proper equipment (1).

Get to Know SYNLAB – A Leading Provider of Medical Diagnostic Services!

Performing accurate and up-to-date tests is essential for precise diagnoses and the best treatment strategies. SYNLAB is here to help.

We offer high-quality diagnostic solutions with strict quality control for companies, patients, and doctors. Present in Brazil for over 10 years, we operate in 36 countries across three continents and are the leading provider of diagnostic services in Europe.

Contact the SYNLAB team and learn more about the available tests!

References

1. World Health Organization. WHO Recommendations on antenatal care for a positive pregnancy experience. Geneva: WHO; 2016.
2. Gomes FC. Triagem pré-natal ampliada: Teste da mamãe, Revista da Faculdade União de Goyazes, Vita et Sanitas 2009; p. 101-109.
3. Ministério da Saúde. Importância do Pré-natal. Biblioteca Virtual em Saúde. Disponível em: https://bvsms.saude.gov.br/importancia-do-pre-natal/
4. Ministério da Saúde. Exames e vacinas. Disponível em: https://www.gov.br/saude/pt-br/assuntos/saude-de-a-a-z/g/gravidez/exames-e-vacinas
5. Norton ME, Jacobsson B, Swamy GK, Laurent LC, Ranzini AC, Brar H, et al. Cell-free DNA Analysis for Noninvasive Examination of Trisomy. N Engl J Med. 2015;372:1589–1597.
6. Chiu RWK, Chan KCA, Gao Y, Lau VYM, Zheng W, Leung TY, Foo CHF, Xie B, Tsui NBY, Lun FMF, Zee BCY, Lau TK, Cantor CR, Lo YMD. Noninvasive prenatal diagnosis of fetal chromosomal aneuploidy by massively parallel genomic sequencing of DNA in maternal plasma. Proc Natl Acad Sci USA 2008; 105: 20458–20463.
7. Abedalthagafi M, Bawazeer S, Fawaz RI, Heritage AM, Alajaji NM, Faqeih E. Non-invasive prenatal testing: a revolutionary journey in prenatal testing. Front Med (Lausanne). 2023 Nov 9;10:1265090.
8. American College of Obstetricians and Gynecologists Committee Opinion No. 640: Cell-Free DNA Screening for Fetal Aneuploidy. Obstet Gynecol. 2015;126:e31-7.
9. Ministério da Saúde. Caderno de Atenção Básica nº 32 – Atenção ao Pré-Natal de Baixo Risco. Disponível em: https://bvsms.saude.gov.br/bvs/publicacoes/cadernos_atencao_basica_32_prenatal.pdf
10. American College of Obstetricians and Gynecologists (ACOG), Practice Bulletin 226 (2020). Disponível em: https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2020/10/screening-for-fetal-chromosomal-abnormalities