Understanding the Double Marker Normal Range: Insights and Importance
Time to read 16 min
Time to read 16 min
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A first-trimester prenatal screening that identifies an increased risk of chromosome abnormalities including Down syndrome and Edwards syndrome is the Double Marker Test which measures two hormones in the blood of the mom including free beta-hCG and PAPP-A.
This is a non-invasive blood test which is usually used together with a Nuchal Translucency scan to provide a holistic analysis of the risk to the baby and assess the baby's genetic health , and may prompt additional diagnostic tests . The test results interpretation does not diagnose a condition, but provides an estimate of risks to enable parents to make a decision about further testing.
The Double Marker Test is a test that is done to determine whether a fetus may have chromosome issues, playing a crucial role in detecting chromosomal abnormalities. and is part of the double marker test procedure . Chromosome issues imply that the baby is either in excess or deficient in chromosomes, which may require invasive tests for confirmation .
Two major substances in the mother blood are measured in the test:
Free Beta-hCG It is a placental hormone.
PAPP-A : It is a kind of protein that assists the placenta to grow.
The values and normal ranges of the dual marker test are significant since they assist in the early detection of chromosome issues in the infant at an early age e.g., Down syndrome, Edwards syndrome or Patau syndrome.
A low-risk outcome implies the possibility of such conditions is extremely low, while a moderate risk outcome indicates further evaluation may be necessary. whereas a moderate or high risk one means that the risk of chromosomal abnormalities is greater, and in this case doctors conduct more tests and help you make the right decision concerning the pregnancy.
Discovery of Risk Levels: The test examines such markers as free beta -hCG and PAPP -A. The results are classified into three categories which are low and moderate and high risk.
Meaning of the Result: When you receive a low-risk result there is a very low possibility that your baby has a genetic problem.
Low-Risk (Normal): It is a risk that is severely low and therefore no further tests are typically required. It can give you peace of mind.
High-Risk: This is because the probability of problems is more probable. To be sure, doctors will commonly recommend further examinations including the Non-Invasive Prenatal Test, amniocentesis or chorionic villus sampling.
The double marker blood test, which is a simple blood test, is generally performed during the period between weeks 11 and 14 of the first trimester and preferably in weeks 11 to 13. It involves a test of the level of hCG and PAPP A in blood to determine whether the infant might be having chromosomal issues like Down syndrome.
Accuracy: The best way to indicate chromosomal issues is through the level of the hormones in the blood of the mother and it is not difficult to measure at this point in time.
Comprehensive Screening: The blood screening is typically conducted simultaneously with a Nuchal Translucency scan, which is an ultrasound, to examine general risk.
The dual marker test is done on two substances in the blood of a pregnant woman. These two substances are; free beta-human chorionic gonadotropin (free beta-hCG) and pregnancy-associated plasma protein-A.
Under normal conditions of the levels of these substances, particularly when accompanied with an ultrasound to check the presence of the nuchal translucency scan, both the mother and doctors can be in a better position to determine the risk that the baby would have chromosomal issues such as Down syndrome, playing a crucial role in detecting chromosomal abnormalities .
Free beta-hCG: This is a hormone produced by the placenta during pregnancy.
PAPP-A: This is a protein produced by the growing placenta.
Blood Sample: A small blood sample is drawn from the mother’s arm.
Lab Examination: The blood is referred to a lab where they examine the amount of free beta-hCG and PAPP-A in the blood.
Combinations with Ultrasound: The laboratory findings are compared to an ultrasound referred to as a nuchal scan and is used to view the space behind the neck of the baby.
Risk Assessment: This combined information provides a risk score which indicates whether the risk of having a chromosome problem is low, moderate, or high.
The double marker test is a prenatal screening which is completed during the first trimester, and the normal values of the test are based on the number of weeks of pregnancy, aiming to identify potential birth defects . The findings are typically presented in Multiples of the Median where 1.0 MoM represents the median of that stage of a normal pregnancy.
Lots of health resources state that the normal outcome in a marker test in pregnancy is a PAPP-A of approximately 1.0 MoM and an 8 -hCG of approximately 1.0 MoM. Other laboratories also provide individual ranges of their reference per week of pregnancy.
|
Gestational Week |
Free Beta-hCG Interval (ng/mL) |
PAPP-A Interval (mIU/mL) |
|
8th week |
53–104 |
<0.99 |
|
9th week |
30.5–213 |
<1.39 |
|
10th week |
17.4–145 |
<1.95 |
|
11th week |
14.9–107 |
<2.75 |
|
12th week |
12.3–99.6 |
<3.86 |
|
13th week |
11.2–88.6 |
<5.43 |
Since the double marker test is a screening tool, not a diagnostic one, the most important aspect of the report is the overall risk assessment, not the individual hormone numbers. These are the typical risk categories reported:
Category |
Typical Result |
Interpretation |
Low Risk |
Screen Negative |
A low probability of chromosomal abnormalities. This is the normal outcome. |
Moderate/High Risk |
Screen Positive |
An elevated risk of abnormalities. Further diagnostic tests, such as NIPT or amniocentesis, may be recommended to confirm a diagnosis. |
The individual outcomes are important: The physician will analyze your results against your age, medical history, and the results of your nuchal translucency (NT) scan.
Risk vs. diagnosis: An abnormal(high-risk) abbreviated double marker test does not mean that your baby has a chromosomal condition. It is just that the probability is greater, and you will have to do more testing to prove it.
See your doctor: You should always discuss your test results on a double marker test with your healthcare provider. They are the best to give you the meaning of your numbers and any future action.
The Double Marker test is performed during the first trimester, preferably between 9 and 13 weeks and helps to detect the risks of chromosomal issues such as Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18). Two substances are tested in maternal serum screening, including PAPP-A and the free beta-hCG.
Physicians, along with a qualified healthcare provider, tend to examine the number of times each level is more than the normal average (the Multiple of Median, MoM) since the crude numbers vary wildly with the progress of the pregnancy and between women.
Since the concentrations of PAPP-A and Free Beta hCG change rapidly in early pregnancy, the most reliable "normal" value is expressed as a Multiple of Median (MoM).
Marker |
Normal Range in MoM (Multiple of Median) |
Normal Trend in IU/L or ng/ml at 13 Weeks |
PAPP-A |
Approximately ≥0.5 MoM |
Levels increase with advancing gestational age. |
Free Beta hCG |
Approximately 0.5 MoM to 2.0 MoM |
Levels decrease after peaking around 10-12 weeks. |
Low Risk (Screen Negative): The mother age, age of the NT scan, and MoM risk ratio are typically larger than the cut off e.g. 1:250. The cut-off may be different in each lab.
High Risk (Screen Positive): The cut-off is a risk ratio that falls below 1:250 which can be an indication that there is an increased risk of a chromosomal abnormality.
Figures such as IU/L, mIU/mL (approximately equivalent to 1 IU/L) or ng/mL differ across laboratories. They also vary according to the specific week of month of pregnancy. The following ranges provide a rough idea of the week 13.
Units: Typically in units of mL i.e. mL of U.
Approximate Range: The figures tend to increase in the range of 13 weeks. Based on the research, the midrange values of PAPP -A can range across 2,500 to 4,500 mIU/L and above depending on the week of pregnancy and the group under consideration.
Units: Typically expressed in mIU/mL or ng/mL, following the blood sample collection during the test . In the case of Free Beta hCG 1 ng/mL would be approximately 1 mIU/mL though this may vary across labs.
Approximate Range in mIU/mL: Free Beta hCG decreases after the peak of the first trimester. A total hCG (not free Beta) of approximately 18,300-137,000mIU/mL is obtained at 12-16 weeks of age. The hCG is made up of the free beta only in part.
Normal Range in ng/mL: The average Free Beta hCG is approximately 30-50 ng/mL at the age of 13 weeks. The normal range may be quite broad such as 10 and beyond 100 ng/mL since the MoM (multiple of the median) is the most important.
MoM refers to the Median Value for Gestational Age Patient's test value. It is a way to standardize medical test value to the median of the reference population.
The equations that convert biomarker measurements to MoMs rely on different factors and they are also from different gestational ages (11+0 to 14+1, 19+0 to 24+6, 30+0 to 34+6, 35+0 to 37+6 weeks).
The levels of Free Beta-hCG and PAPP-A are compared to the average (median) values expected for a normal pregnancy at the same gestational age. This comparison is expressed as the MoM.
A normal MoM value for both markers is typically around 1.0 MoM (ranging from approximately 0.5 to 2.5 MoM, depending on the marker and gestational age).
|
Condition |
Free Beta-hCG MoM |
PAPP-A MoM |
|
Down Syndrome (Trisomy 21) |
Significantly High (e.g., ≥ 2.0 MoM) |
Significantly Low (e.g., ≤ 0.5 MoM) |
|
Edwards Syndrome (Trisomy 18) |
Significantly Low (e.g., ≤ 0.3 MoM) |
Significantly Low (e.g., ≤ 0.3 MoM) |
It estimates the risk of pregnancy complication like Down's syndrome and Preeclampsia.
MoM finds out maternal characteristics, medical history and gestational age.
Normalization: The MoM simplifies the process of comparing the test numbers due to elimination of the variation that arise when different units are used such as IU/L and ng/mL and also applies to babies at various stages of pregnancy.
Risk Assessment: Under normal pregnancy, the MoM value is approximately 1.0. When the value is not close to 1.0, it means that there is a high chance of a problem. The PAPP-A MoM is normally lower than 0.5 and Free Beta hCG MoM is normally higher than 2.0 in the case of Down Syndrome. In the case of Edwards Syndrome, the PAPP-A MoM and the Free Beta hCG MoM both tend to be less than 0.5.
The last risk is computed by combining the MoMs of PAPP-A, free beta hcg, and Nuchal Translucency (NT) measurement of the ultrasound and the age of the mother.
MoM Value |
Meaning |
|---|---|
~1.0 |
Normal (same as median) |
< 0.5 |
Lower than average |
> 2.0 |
Higher than average – may indicate higher risk depending on the marker |
A high AFP MoM (>2.5) might suggest a neural tube defect.
A high hCG MoM could be associated with increased risk of Down syndrome.
The dual marker blood test, also known as the Dual Marker Test or First Trimester Screening, is a standard blood test in the course of the pregnancy. It verifies the possibility of the baby to have Down syndrome or Edwards syndrome (trisomy 18).
Here is a breakdown of the information you requested:
The Double Marker Test is part of the first-trimester screening and is typically performed during 11-week to 13-weeks of pregnancy. The test is most commonly performed alongside a Nuchal Translucency (NT) ultrasound scan.
The report will typically show the levels of two specific markers measured in the mother's blood, along with a calculated risk assessment:
Free Beta-human Chorionic Gonadotropin (Free 2-hCG)
Pregnancy-Associated Plasma Protein-A (PAPP-A)
These values tend to be expressed in real numbers and also in Multiples of Median which are an indication of the level of the measurement as compared to the average level supposed to be attained by a pregnancy at the same stage.
The test combines the data of the two markers. the age of the mother, her weight and the NT scan reading to provide a personal risk ratio to certain chromosomal diseases such as Down syndrome and Trisomy 18.
These are displayed as ratios, e.g. 1:1000 or 1:250.
The last risk is considered as a low risk when the screen is negative and as a high risk when the screen is positive.
A normal report will indicate a Screen Negative or Low Risk result.
High risk: A 1 to 250 or greater (i.e., to 1000 or 5000) ratio is considered to be low risk. This implies that the baby will not be prone to the condition.
Markers MoM (approximately normal range): In the case of both PAPP-A and Free -hcg, a MoM of about 1.0 is normal where the screen result is negative. Laboratories may have a different specific normal range.
Marker |
Abnormality |
PAPP-A Level |
Free β-hCG Level |
Down Syndrome (Trisomy 21) |
High Risk |
Lower than normal (low MoM) |
Higher than normal (high MoM) |
Edwards Syndrome (Trisomy 18) |
High Risk |
Significantly Lower than normal (very low MoM) |
Significantly Lower than normal (very low MoM) |
The Double Marker Test is a test that examines whether there are problems but it does not determine their existence. High Risk result only implies that the probability is greater, it does not imply that the baby does have it, whereas a double marker test negative result suggests an extremely low likelihood .
In the event of high risk outcome, your physician might suggest additional tests like Non-Invasive Prenatal Testing (NIPT), Chorionic Villus Sampling (CVS) or Amniocentesis to seek a clear diagnosis.
The time to receive the report can vary between laboratories, but generally, the results are available within:
2 to 7 days (or 3 to 5 working days) after the blood sample is collected.
The dual marker test or the pregnancy double marker test is a non-invasive prenatal screening test which is normally performed within the first trimester. It is used to detect the possibility that the fetus may be having some chromosomal abnormality, which is crucial for pregnant women, most frequently Down syndrome or Edwards syndrome.
This is a screening test, not a diagnosis test. It will never say yes or no, only approximate what the risk will be. The findings are ordinarily paired with an ultrasound test known as the nuchal translucency (NT) scan to provide a more reliable test.
Here is a guide on how to understand the report's key indicators, which are essential for monitoring the health of the developing baby.
The test measures the levels of two specific substances in the mother's blood:
Free Beta-hCG (Human Chorionic Gonadotropin): A hormone produced by the placenta.
PAPP-A (Pregnancy-Associated Plasma Protein-A): A protein produced by the placenta.
The report presents the levels of these markers, often as a MoM (Multiple of the Median) value, and then calculates an overall Risk Ratio.
The most important part of the report is the calculated risk ratio, which is expressed as a fraction (e.g., 1:100, 1:1000).
|
Risk Category |
Example Ratio |
Interpretation |
|
Normal (Low Risk) |
1:1000 or greater (e.g., 1:1500) |
This is considered a "Screen Negative" result. It suggests a low probability of the baby having the chromosomal abnormality. |
|
Abnormal (High Risk) |
1:250 or less (e.g., 1:150, 1:50) |
This is considered a "Screen Positive" result. It suggests an increased probability (higher chance) of the genetic condition. Further diagnostic testing is usually recommended. |
It is a Screening Tool: A positive result on a test that claims to be a high-risk baby (screen positive) does not imply that the baby has a problem. It only implies that the probability is increased and you require more and more conclusive tests like NIPT, amniocentesis or chorionic villus sampling (CVS) to prove or disprove the condition.
It Incorporates other Factors: The last risk figure is determined by the level of the marker, the mother age, and the value of nuchal translucency (NT) scan. The age of a mother particularly above 35 years is a significant determinant that increases the baseline risk.
Consult Your Doctor: A healthcare provider is only able to read the report and examine it thoroughly, considering your medical history, the NT scan results, and all the biochemical values. Do not attempt to interpret the results or arrive at decisions without consulting a doctor.
The Double Marker Test is a significant early screening test, which is conducted during the first trimester to determine the probability of certain chromosome defects, including chromosomal abnormalities such as Down syndrome and Edwards syndrome. A double marker test positive result may indicate the need for further testing It should be remembered that this test is a screening test but it does not diagnose genetic conditions .
A double marker test normal report reveals that the concentrations of the Free Beta hCG and PAPP-A are equal and the probability of the chromosomal abnormalities like Down syndrome or Trisomy 18 is minimal. The MoM (Multiple of Median) value is normally within the range of 0.5 to 2.0, which contributes to providing accurate results regarding the risk of chromosomal abnormalities . This finding implies that the baby's health and genetic health is normal and healthy development.
Yes, the 13 weeks test is a good one, especially when the double marker test performed at this time can provide accurate readings. The time is best since the concentration of pregnancy hormones can be determined well. It is used in combination with ultrasound results and provides a more accurate picture of the baby as to its potential genetic issue. The accuracy of testing after this period might not be so high.
A MoM (Multiple of the Median) value greater than 2.0 can be considered abnormal. When the value is above 2.0, it means the level of that marker in your blood is more than twice the median. It indicates an increased risk for certain conditions. For example, a high AFP (alpha-fetoprotein) MoM value—typically above 2.5 is associated with neural tube defects such as spina bifida. Similarly, elevated levels of hCG (human chorionic gonadotropin) may be seen in pregnancies at higher risk for chromosomal abnormalities like Down syndrome.
Yes, the test units and reference range may vary across laboratories, and so does the double marker test cost, which can be influenced by the specific lab's pricing structure . This is because various machines, reagents and methods are employed. Before reading your report, get its normal range as provided by your lab. Never compare reports with other labs with those of your doctor.
In the case of the double marker test being out of the normal range. It implies that there may be increased risk of genetic issues in the baby. But this does not imply that the baby is not healthy. To be more certain and not to be worried, it is advisable to seek professional medical advice, particularly if there is a family history of genetic issues and the doctor can recommend other tests, including NIPT or detailed ultrasound.
* Medical Disclaimer - The following information is for educational purposes only. No information provided on this website, including text, graphic, and images, are intended as substitutes for professional medical advice. Please consult with your doctor about specific medical advice pertaining to your condition(s).
