Down Syndrome Signs During Pregnancy | Cadabam's CDC

Signs And Symptoms Of Down Syndrome During Pregnancy

During pregnancy, Down syndrome does not cause physical symptoms or noticeable discomfort in the expectant mother. Instead, the signs and symptoms of Down syndrome during pregnancy refer to specific radiological "soft markers" seen on fetal ultrasounds and abnormal protein levels detected in maternal blood screening tests. A confirmed diagnosis requires diagnostic procedures such as Chorionic Villus Sampling (CVS) or amniocentesis.

What is signs and symptoms of down syndrome during pregnancy?

Down syndrome, clinically known as Trisomy 21, is a genetic condition caused by the presence of an extra copy of chromosome 21. When parents search for the signs and symptoms of Down syndrome during pregnancy, it is important to understand that the pregnant mother will not experience typical physical illness, morning sickness changes, or distinct abdominal sensations related to the condition.

In a clinical context, "signs" refer to measurable anatomical indicators observed on a fetal ultrasound or biochemical markers evaluated in a pregnant woman's blood. In India, prenatal protocols established by fetal medicine guidelines and supported by organizations like the Indian Council of Medical Research (ICMR) recommend routine screening to assess the probability of chromosomal variations during the first and second trimesters.

Prenatal screening does not diagnose Down syndrome directly; rather, it identifies whether a pregnancy falls into a low-risk or high-risk category. If screening scans or blood tests reveal potential indicators, expectant parents are offered non-invasive or invasive diagnostic tests to obtain clear genomic confirmation. Understanding these prenatal signs helps families make informed medical decisions and plan for early developmental support from birth.

Signs and Symptoms

Prenatal signs of Down syndrome are divided into first-trimester markers, second-trimester ultrasound markers, and maternal blood biomarker patterns. Fetal medicine specialists evaluate these indicators together to calculate a personalized risk assessment.

1. First-Trimester Indicators (Weeks 11 to 13 + 6 days)

The first trimester screening combines a specialized ultrasound scan with maternal blood tests to detect early structural and biochemical signs:

• Increased Nuchal Translucency (NT): The NT scan measures the clear fluid space at the back of the fetal neck. A measurement greater than 3.0 mm to 3.5 mm often indicates an increased risk for Down syndrome or cardiac anomalies.
• Absent or Hypoplastic Nasal Bone: In approximately 60% to 70% of fetuses with Down syndrome, the nasal bone is not clearly visible during the 11–13 week ultrasound scan.
• Altered Blood Biomarkers: A maternal serum blood test evaluates two key proteins. Low levels of Pregnancy-Associated Plasma Protein-A (PAPP-A) combined with elevated levels of Free Beta-Human Chorionic Gonadotropin (Free β-hCG) are classic biochemical signs of Trisomy 21.

2. Second-Trimester "Soft Markers" (Weeks 18 to 22)

During the detailed Level II anomaly scan, fetal radiographers search for structural "soft markers." While soft markers can occur in neurotypical fetuses, their presence in combination increases the likelihood of Trisomy 21:

• Echogenic Intracardiac Focus (EIF): A bright spot seen in the fetal heart muscle on ultrasound, caused by minor calcium deposits.
• Short Femur or Humerus Length: The measurement of the upper leg (femur) or upper arm (humerus) bone is shorter than expected for the fetus's gestational age.
• Echogenic Bowel: The fetal intestine appears as bright white as surrounding bone on the ultrasound image.
• Mild Ventriculomegaly: Mild fluid enlargement within the lateral ventricles of the fetal brain (measuring 10 to 12 mm).
• Renal Pyelectasis: Minor fluid retention or swelling in the pelvis of the fetal kidneys.

Prenatal Screening vs. Diagnostic Testing Options

To clarify how these signs are evaluated clinically, the table below outlines the common screening and diagnostic procedures used during pregnancy:

Test Name	Type of Test	Recommended Timing	Detection Rate / Accuracy	Primary Purpose
Combined First-Trimester Screen	Screening (Blood + Ultrasound)	11 – 13+6 weeks	85% – 90%	Evaluates NT thickness, nasal bone, PAPP-A, and β-hCG levels.
Non-Invasive Prenatal Testing (NIPT)	Cell-free DNA Blood Screen	From 10 weeks onward	> 99%	Analyzes fetal DNA circulating in maternal blood for Trisomy 21.
Quadruple Marker Screen	Second-Trimester Blood Screen	15 – 20 weeks	75% – 81%	Measures AFP, hCG, Estriol (uE3), and Inhibin-A levels.
Chorionic Villus Sampling (CVS)	Invasive Diagnostic Test	10 – 13 weeks	> 99.5%	Analyzes placental tissue samples to confirm fetal chromosomes.
Amniocentesis	Invasive Diagnostic Test	15 – 20 weeks	> 99.5%	Analyzes fetal cells from amniotic fluid for definitive diagnosis.

When to Seek Help

Navigating prenatal screening results can be complex and emotionally challenging for expecting parents. It is essential to consult a qualified obstetrician, fetal medicine specialist, or genetic counselor under the following circumstances:

• Maternal Age Over 35: The statistical probability of Trisomy 21 increases with maternal age. At age 35, the chance is approximately 1 in 350, rising to 1 in 100 by age 40.
• High-Risk Screening Result: If a First-Trimester Combined Screen, Quadruple Screen, or NIPT indicates a high probability for Down syndrome.
• Multiple Soft Markers on Ultrasound: If a mid-trimester anomaly scan identifies two or more ultrasound soft markers.
• Previous History: Families who have a previous child or pregnancy affected by a chromosomal condition.

Receiving a high-risk result or a confirmed prenatal diagnosis can feel overwhelming. Seeking professional guidance early allows families to meet with pediatric developmental experts, learn about early intervention strategies, and prepare a supportive medical environment for their child's arrival.

How Cadabam's CDC Can Help

At Cadabam's Child Development Centre in Bangalore, we provide comprehensive, family-centered support for children with Down syndrome and their families. Our multidisciplinary team of developmental pediatricians, speech therapists, occupational therapists, and special educators works together to design early intervention plans tailored to your child's unique needs.

Whether you are seeking guidance after prenatal screening or preparing for early developmental support from birth, we are here to help your family every step of the way.

To learn more about our services or schedule a consultation, please contact Cadabam's CDC today.

---

Disclaimer: This content is for general information only and is not a substitute for professional medical advice. Always consult a qualified professional for a formal assessment.