MFM Patient Counseling

Consanguinity
& Pregnancy

What you need to know about related-couple pregnancies, genetic risks, and our monitoring plan

Genetics Reassurance Screening ACOG / SMFM

Definition

What Does "Consanguinity" Mean?

      A pregnancy between two individuals who share a common ancestor — such as first cousins or closer relatives.
    

"Consanguineous" literally means "of the same blood" — defined as second cousins or closer.

Prevalence

You Are Not Alone

~10%

of the world's population is born from consanguineous unions

Middle East South Asia North Africa Sub-Saharan Africa Parts of Europe & Americas

Our team provides non-judgmental, culturally sensitive care for every family.

Genetics

Why Does It Matter Genetically?

Carrier × Carrier Cross

Cc

Carrier
Parent 1

×

Cc

Carrier
Parent 2

↓

CC

Normal
25%

Cc

Carrier
50%

cc

Affected
25%

Shared DNA

Related parents share more of their genetic code than unrelated couples.

Hidden Variants

Both may unknowingly carry the same recessive gene mutation from a common ancestor.

25% Chance

If both are carriers of the same variant, each pregnancy has a 1-in-4 chance of being affected.

Risk Assessment

Risk Depends on How Closely You Are Related

Relationship	Inbreeding Coefficient (F)	Birth Defect Risk	vs. Baseline
General Population	—	2–3%	Baseline
Second Cousins	0.016	~2–3%	Near baseline
First Cousins	0.0625	4–6%	~2× baseline
First-Degree (Incest)	0.25	7–31%	Up to 10× baseline

      For first-cousin unions: absolute risk ~4–6% — meaning 94–96% of babies are unaffected.
    

Fetal Risks

Conditions We Screen For

🧬

Recessive Disorders

Cystic fibrosis, SMA, sickle cell, PKU, and others

❤️

Congenital Heart

Structural cardiac defects — most common major anomaly

🧠

Neural Tube Defects

Spina bifida, anencephaly — elevated in consanguinity

🦴

Skeletal Anomalies

Limb differences and skeletal dysplasias

      These are the structures we focus on during your detailed anatomy ultrasound at 18–22 weeks.
    

Pregnancy Outcomes

Other Pregnancy Risks to Know

⏰ Preterm Birth

Delivery before 37 weeks — modestly elevated risk

📏 Small Baby (SGA)

Small-for-gestational-age — related to placentation

💔 Stillbirth

Odds ratio ~1.4 — slightly elevated above baseline

👶 Neonatal Death

Elevated risk, often linked to lethal recessive conditions

          These risks are real — but manageable.

          Close monitoring significantly reduces uncertainty.

          Most adverse outcomes are linked to undetected recessive conditions — which is exactly why we screen.
        

Screening Protocol — Step 1

Building Your Family Tree

      We document at least 3 generations of your family history — looking for genetic conditions, unexplained infant deaths, or recurrent pregnancy losses.
    

Known hereditary conditions Unexplained infant deaths Recurrent miscarriages Hearing / vision loss

Screening Protocol — Step 2

Expanded Carrier Screening (ECS)

🧪 What Is It?

A blood or saliva test that checks whether both partners carry the same recessive gene mutations.

👫 Both Partners

Offered to both of you. Consanguineous couples have a higher detection rate of shared mutations.

✅ If Negative

No shared mutations found — highly reassuring. Residual risk remains low.

⚠️ If Both Carriers

25% chance per pregnancy of an affected child. Diagnostic testing will be discussed.

🔬 Panel Options

Standard pan-ethnic panel or Whole Exome Sequencing (WES) for broader coverage.

          Note: ECS does not capture all rare or de novo mutations. We will explain every result.
        

Screening Protocol — Step 3

First-Trimester Ultrasound & Labs

11

Weeks

14

Weeks

First-Trimester Screening Window

📡 Nuchal Translucency

Ultrasound measurement of fluid at the back of the baby's neck — screens for chromosomal conditions.

🩸 Blood Tests

PAPP-A and free β-hCG — combined with NT for Down syndrome and trisomy 18/13 risk.

      Consanguinity alone does not require invasive testing at this stage — unless other risk factors are present.
    

Screening Protocol — Step 4

Detailed Anatomy Scan at 18–22 Weeks

🧠 Brain & Spine

Neural tube closure, cerebral ventricles, posterior fossa

❤️ Heart (4-View)

Cardiac chambers, outflow tracts — most common major anomaly site

🦴 Limbs & Skeleton

Long bone lengths, hands, feet — skeletal dysplasias

🫁 Abdominal Organs

Kidneys, bladder, abdominal wall integrity

Screening Protocol — Step 5

Diagnostic Testing (If Indicated)

🧫

Chorionic Villus Sampling (CVS)

Performed at 10–13 weeks

A small sample of placental tissue is taken to analyze the baby's chromosomes and genes.

Earlier result

💉

Amniocentesis

Performed at 15+ weeks

A small sample of amniotic fluid is taken to analyze the baby's genetic material.

Gold standard

      Diagnostic testing is offered only when carrier screening identifies a shared pathogenic mutation in both partners, or when ultrasound findings suggest a specific condition.
    

Genetic Results

Understanding Your Results

✅

Negative / Normal

No shared pathogenic mutations found. Highly reassuring — residual risk remains low.

⚠️

Variant of Uncertain Significance (VUS)

Unclear meaning. Do not panic. Most VUS findings do not cause disease. We will monitor and re-classify over time.

🔴

Pathogenic / Likely Pathogenic

A known disease-causing variant. We will discuss options, surveillance, and next steps together.

      Important: Not all genetic variants cause disease. We focus counseling on pathogenic or likely pathogenic findings only.
    

Your Care Plan

You Have a Team

👨‍⚕️

MFM Specialist

Oversees high-risk pregnancy management and fetal surveillance

🧬

Genetic Counselor

Interprets carrier screening and diagnostic results

🔬

Sonographer

Performs detailed anatomy and targeted fetal surveillance scans

Three-generation family history documented
Expanded Carrier Screening ordered for both partners
First-trimester ultrasound and labs scheduled
Detailed anatomy scan at 18–22 weeks confirmed
Counseling provided on all findings and limitations

Summary

Key Takeaways

✅ Most Babies Are Healthy

First-cousin unions: 94–96% of babies are unaffected

📊 Quantified Risk

~4–6% birth defect risk (vs. 2–3% baseline) for first cousins

🔬 Screening Works

Carrier screening + anatomy scan significantly reduces uncertainty

🤝 Partnership Care

Non-directive, culturally sensitive counseling — your autonomy is respected

      ACOG & SMFM guidelines support this care plan. We are your partners in this pregnancy — every step of the way.
    

Questions? Ask your MFM specialist today.

Consanguinity& Pregnancy