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What is a double marker test in pregnancy
Dec 05, 2025
In the first trimester, screening helps estimate the chance of certain chromosomal conditions because early knowledge supports calmer, better-timed decisions; therefore most care plans include a double marker test together with the 11–13 + 6-week ultrasound. Teams at BirthRight by Rainbow Hospitals usually coordinate these in the same window so results are interpreted together.
FAQs
What exactly does the double marker test in pregnancy tell me—does it diagnose anything?
It’s a screen, not a diagnosis. It estimates the chance of certain chromosomal conditions (mainly Trisomy 21 and 18) because it combines your age, exact gestation, NT scan, and two blood markers (free β-hCG, PAPP-A); therefore it guides whether further testing would help, not whether a condition is present.
Why must the blood test and NT scan be done around 11–13 + 6 weeks?
That window gives the most reliable nuchal translucency (NT) and the most accurate hormone “MoM” adjustments because fetal size and placental signals change rapidly; therefore doing both in the same week usually produces a clearer risk estimate.
My report says “high risk.” What are the next options and why?
Clinicians generally discuss NIPT to refine risk without procedure risk, or CVS/Amniocentesis to confirm or rule out by testing fetal chromosomes directly—because a screen can only estimate; therefore diagnostic steps are needed to know for sure.
Can anything make the values look off even if the baby is fine?
Yes—incorrect dating, twins, higher maternal weight, smoking, diabetes, or IVF can shift β-hCG or PAPP-A because they alter placental hormone levels; therefore labs adjust for these and note them on the report so interpretation stays fair.
Disclaimer: The information above is for general education. It is not medical advice and does not replace an in-person evaluation or your clinician’s recommendations.
What the double marker test in pregnancy measures
A double marker blood test in pregnancy analyzes two substances in the mother’s blood:- Free β-hCG (a pregnancy hormone), and
- PAPP-A (pregnancy-associated plasma protein-A).
When it’s done—and why the window matters
The usual window is 11 weeks to 13 weeks + 6 days. NT is most reliable then, so the software can calculate a more accurate chance of Down syndrome (Trisomy 21) and Trisomy 18.What screening means here
Screening estimates probability. Results are reported as odds (e.g., 1 in 800) or categories (low/average/high). A higher-risk screen does not mean the baby is affected; but it signals that confirmatory testing may be useful. A lower-risk screen reduces the chance; therefore routine care continues, but risk is not zero.How labs interpret the numbers—without jargon
Labs convert raw hormone levels into MoM (multiple of the median) to adjust for gestational age and other factors.- Higher β-hCG with lower PAPP-A can raise the calculated chance for Trisomy 21, because placental hormone patterns shift; therefore the combined risk may cross a threshold.
- Lower β-hCG and lower PAPP-A can raise the calculated chance for Trisomy 18.
These are tendencies—not stand-alone rules—so the NT value and dating accuracy carry significant weight.
What follows after the result
- If the calculated risk is low: antenatal care generally continues as planned, because the chance is small; therefore no further genetic testing is usually needed for that concern.
- If the calculated risk is higher: clinicians may suggest one of the following, because only these can refine or confirm:
- NIPT (non-invasive prenatal testing): analyzes fetal DNA in maternal blood; therefore it refines risk without procedure-related miscarriage risk.
- CVS (chorionic villus sampling) at ~11–14 weeks or amniocentesis after ~15 weeks: diagnostic tests that examine fetal chromosomes directly; therefore they can confirm or rule out a condition; but they carry a small procedure-related risk, so counselling comes first.
- NIPT (non-invasive prenatal testing): analyzes fetal DNA in maternal blood; therefore it refines risk without procedure-related miscarriage risk.
Factors that can influence the report
Incorrect dates, twins, higher maternal weight, smoking, diabetes, or IVF conception can shift hormone levels; therefore labs adjust when possible and usually note these on the report so interpretation remains fair.What the appointment is like
It involves a standard blood draw from a vein. Reports usually show β-hCG and PAPP-A values (with MoM), the NT measurement, and a combined risk. Turnaround is often a few working days, because the lab must process the sample and run the risk model; therefore many centres schedule the blood test and NT scan in the same week.How the double marker fits into first-trimester care
- Dating scan: confirms gestational age, because accurate dating anchors MoM; therefore most labs request the scan report.
- NT scan (11–13 + 6 weeks): adds critical data, so combined risk is stronger.
- Early anatomical review (where available): structural findings can modify risk; therefore results are considered together.
Key takeaways
- The double marker test in pregnancy is a screen, because it estimates probability; therefore it guides whether further testing is helpful.
- Results make the most sense with the NT measurement and correct dating, so coordinated scheduling improves accuracy.
- Higher-risk screens usually lead to options like NIPT or diagnostic testing; therefore counselling supports an informed choice that matches family preferences.
- Care pathways at places like BirthRight by Rainbow Hospitals aim to combine blood results and ultrasound findings in one consult, so next steps are clear without delay.
FAQs
What exactly does the double marker test in pregnancy tell me—does it diagnose anything?
It’s a screen, not a diagnosis. It estimates the chance of certain chromosomal conditions (mainly Trisomy 21 and 18) because it combines your age, exact gestation, NT scan, and two blood markers (free β-hCG, PAPP-A); therefore it guides whether further testing would help, not whether a condition is present.
Why must the blood test and NT scan be done around 11–13 + 6 weeks?
That window gives the most reliable nuchal translucency (NT) and the most accurate hormone “MoM” adjustments because fetal size and placental signals change rapidly; therefore doing both in the same week usually produces a clearer risk estimate.
My report says “high risk.” What are the next options and why?
Clinicians generally discuss NIPT to refine risk without procedure risk, or CVS/Amniocentesis to confirm or rule out by testing fetal chromosomes directly—because a screen can only estimate; therefore diagnostic steps are needed to know for sure.
Can anything make the values look off even if the baby is fine?
Yes—incorrect dating, twins, higher maternal weight, smoking, diabetes, or IVF can shift β-hCG or PAPP-A because they alter placental hormone levels; therefore labs adjust for these and note them on the report so interpretation stays fair.
Disclaimer: The information above is for general education. It is not medical advice and does not replace an in-person evaluation or your clinician’s recommendations.
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