Tests During Twin Pregnancy: All Scans and Important Checkups

Discovering that you are expecting twins can be an exciting and emotional experience.

Along with the joy often comes a new set of questions and concerns, especially when you learn that twin pregnancies usually require closer monitoring than singleton pregnancies.

Common questions include:

• Why do twin pregnancies need extra monitoring?
• How often will ultrasounds be performed?
• What tests are required during the third trimester?
• How are complications detected?
• Will I need more hospital visits?

Twin pregnancies are considered higher risk than singleton pregnancies because they are associated with:

increased rates of complications such as preterm birth, fetal growth restriction, gestational diabetes, preeclampsia, and placental disorders.

Fortunately, advances in prenatal monitoring have dramatically improved outcomes for both mothers and babies.

As a women’s health physiotherapist, I often reassure expectant mothers that additional monitoring does not necessarily mean something is wrong.

Rather, these tests help healthcare providers identify potential problems early and provide timely intervention when necessary.

Understanding the various monitoring tests used during twin pregnancy can help reduce anxiety and improve confidence throughout your pregnancy journey.

Why Do Twin Pregnancies Need Additional Monitoring?

Twin pregnancies place greater demands on both the mother and the placenta.

Compared with singleton pregnancies, twin pregnancies have increased risks of:

• Fetal growth restriction.
• Preterm birth.
• Preeclampsia.
• Placental insufficiency.
• Gestational diabetes.
• Twin-to-twin transfusion syndrome (TTTS).
• Cesarean birth.

Because of these risks, healthcare providers perform more frequent surveillance to optimize maternal and fetal outcomes.

According to the American College of Obstetricians and Gynecologists (ACOG),

multifetal gestations require individualized antenatal surveillance because of their increased risk of maternal and fetal complications.

Understanding Twin Types: Why Chorionicity Matters

One of the most important early pregnancy assessments determines:

• Chorionicity (whether twins share a placenta).
• Amnionicity (whether twins share an amniotic sac).

Twin pregnancies may be classified as:

Dichorionic Diamniotic (DCDA) Twins

Each baby has:

• Its own placenta.
• Its own amniotic sac.

These pregnancies generally carry the lowest risk among twin pregnancies.

Monochorionic Diamniotic (MCDA) Twins

The babies:

• Share one placenta.
• Have separate amniotic sacs.

These pregnancies require closer surveillance because complications such as TTTS may develop.

Monochorionic Monoamniotic (MCMA) Twins

The babies:

• Share one placenta.
• Share one amniotic sac.

These pregnancies carry the highest risk and require intensive monitoring.

Research demonstrates that chorionicity strongly influences pregnancy outcomes and surveillance schedules (Khalil et al. 2016).

Monitoring Test 1: Routine Prenatal Visits

Women carrying twins usually attend antenatal appointments more frequently than women carrying one baby.

Appointments commonly include:

• Weight assessment.
• Blood pressure measurement.
• Symptom review.
• Fundal height assessment.
• Fetal heart rate monitoring.
• Review of fetal movements.

Visit frequency typically increases during the third trimester.

Depending on pregnancy type and complications, appointments may occur:

• Every 4 weeks initially.
• Every 2 weeks during the second trimester.
• Weekly or twice weekly later in pregnancy.

Monitoring Test 2: Ultrasound Examinations

Ultrasound is the cornerstone of twin pregnancy monitoring.

Routine ultrasound assessments evaluate:

• Fetal growth.
• Amniotic fluid volume.
• Placental function.
• Fetal anatomy.
• Fetal position.
• Umbilical cord assessment.

Twin pregnancies generally undergo significantly more ultrasounds than singleton pregnancies.

Early Dating and Chorionicity Scan

An early ultrasound performed during the first trimester helps determine:

• Gestational age.
• Number of babies.
• Chorionicity.
• Viability.

Accurate determination of chorionicity early in pregnancy is essential because it guides the entire monitoring plan.

Monitoring Test 3: Growth Ultrasounds

Growth scans are among the most important monitoring tests in twin pregnancies.

These scans assess:

• Estimated fetal weight.
• Head circumference.
• Abdominal circumference.
• Femur length.
• Growth trends over time.

Twin pregnancies have an increased risk of fetal growth restriction.

Serial growth assessment allows healthcare providers to detect:

• Growth restriction.
• Growth discordance.
• Placental insufficiency.

Growth discordance refers to a significant difference in size between twins.

Many clinicians consider a weight difference of 20% or more clinically important.

The International Society of Ultrasound in Obstetrics and Gynecology recommends serial growth assessment throughout twin pregnancies.

Citation: ISUOG Practice Guidelines: role of ultrasound in twin pregnancy. PMID: 34951715.

Monitoring Test 4: Amniotic Fluid Assessment

Ultrasound also evaluates the amount of amniotic fluid surrounding each baby.

Abnormal fluid volumes may indicate:

• Placental dysfunction.
• Twin-to-twin transfusion syndrome.
• Fetal abnormalities.
• Ruptured membranes.

Healthcare providers assess:

• Deepest vertical pocket.
• Relative differences between twins.

In monochorionic pregnancies, fluid assessment is especially important because marked differences may suggest TTTS.

Monitoring Test 5: Twin-to-Twin Transfusion Syndrome (TTTS) Screening

Monochorionic twins share placental blood vessels.

Abnormal blood vessel connections can occasionally cause TTTS.

In TTTS:

• One twin (donor twin) transfers blood to the other twin (recipient twin).
• The donor twin may develop growth restriction and reduced amniotic fluid.
• The recipient twin may develop excessive amniotic fluid and cardiovascular strain.

Because TTTS can progress rapidly, monochorionic pregnancies often undergo ultrasound surveillance every two weeks beginning at approximately 16 weeks.

The Society for Maternal-Fetal Medicine recommends close surveillance for monochorionic twins because early diagnosis improves outcomes (Society for Maternal-Fetal Medicine Consult Series #72 et al. 2024)

Monitoring Test 6: Doppler Ultrasound Studies

Doppler ultrasound evaluates blood flow between the placenta and babies.

Common Doppler assessments include:

Umbilical Artery Doppler

Evaluates placental resistance and blood flow.

Middle Cerebral Artery Doppler

Assesses fetal adaptation to reduced oxygen supply.

Ductus Venosus Doppler

May be performed in selected complicated pregnancies.

Doppler studies are particularly valuable when:

• Growth restriction exists.
• TTTS is suspected.
• Placental insufficiency develops.

Monitoring Test 7: Cervical Length Measurement

Twin pregnancies have a significantly increased risk of preterm birth.

Transvaginal ultrasound measurement of cervical length helps identify women at increased risk.

A shortened cervix may indicate increased risk of spontaneous preterm birth.

Women with cervical shortening may require:

• Increased surveillance.
• Activity modification.
• Additional interventions.

Research demonstrates that cervical length is an important predictor of preterm birth in twin pregnancies.(Romero et al. 2017)

Monitoring Test 8: Blood Pressure Monitoring

Women carrying twins have an increased risk of:

• Gestational hypertension.
• Preeclampsia.

Blood pressure is assessed at every antenatal visit.

Some women may also be advised to:

• Monitor blood pressure at home.
• Record symptoms.
• Report abnormal readings immediately.

Monitoring Test 9: Maternal Blood Tests

Twin pregnancies may require additional blood investigations.

Common tests include:

• Complete blood count.
• Iron studies.
• Blood glucose testing.
• Liver function tests.
• Kidney function tests.

Twin pregnancies are associated with increased rates of:

• Iron-deficiency anemia.
• Gestational diabetes.
• Hypertensive disorders.

Regular blood testing helps identify complications early.

A Physiotherapist’s Perspective: Extra Monitoring Is Reassuring

As a women’s health physiotherapist, I often remind mothers expecting twins that increased testing and surveillance are designed to provide reassurance and early detection of complications.

Many twin pregnancies progress normally, and additional monitoring helps healthcare providers support the safest possible outcomes for both mother and babies.

Attending all scheduled appointments remains one of the most important aspects of twin pregnancy care.

Monitoring Test 10: Non-Stress Test (NST)

As twin pregnancies progress into the third trimester, healthcare providers may recommend Non-Stress Tests (NSTs) to assess fetal well-being.

During an NST:

• Sensors are placed on the mother’s abdomen.
• The heart rate of each baby is monitored separately.
• Fetal movements are recorded.
• Heart rate responses to movements are assessed.

A reactive NST, in which the babies’ heart rates appropriately increase with movement, is generally reassuring.

NSTs are commonly recommended in twin pregnancies complicated by:

• Hypertensive disorders.
• Gestational diabetes.
• Fetal growth restriction.
• Reduced fetal movements.
• Placental insufficiency.

Many women with uncomplicated twin pregnancies may also undergo routine antenatal fetal surveillance during the third trimester.

Monitoring Test 11: Biophysical Profile (BPP)

A Biophysical Profile (BPP) combines ultrasound assessment with fetal heart rate monitoring.

Each baby is evaluated individually.

The BPP assesses:

1. Fetal breathing movements.
2. Gross body movements.
3. Fetal muscle tone.
4. Amniotic fluid volume.
5. Non-Stress Test findings.

Each parameter receives a score, helping healthcare providers determine fetal well-being.

Low scores may suggest fetal compromise and prompt closer monitoring or delivery.

Monitoring Test 12: Daily Fetal Movement Assessment

Mothers expecting twins are encouraged to become familiar with their babies’ normal movement patterns.

Although distinguishing between the movements of each baby may be difficult, overall fetal activity remains an important indicator of fetal well-being.

Contact your healthcare provider promptly if you notice:

• Significant reduction in overall fetal movements.
• A sudden change in usual movement patterns.
• No movements for a prolonged period.

Reduced fetal movement warrants urgent medical evaluation because it may indicate fetal compromise.

Monitoring Monochorionic Twins During the Third Trimester

Monochorionic twins require particularly close monitoring because they share a placenta.

Complications requiring intensive surveillance include:

• Twin-to-twin transfusion syndrome (TTTS).
• Selective fetal growth restriction.
• Twin anemia-polycythemia sequence (TAPS).
• Placental insufficiency.

Monitoring often includes:

• Ultrasound every one to two weeks.
• Frequent amniotic fluid assessment.
• Doppler studies.
• Growth scans.
• Fetal surveillance tests.

The International Society of Ultrasound in Obstetrics and Gynecology recommends serial surveillance throughout pregnancy in monochorionic twins because complications may develop rapidly.

Hospital Admission and Inpatient Monitoring

Some women carrying twins require hospitalization during pregnancy.

Reasons for admission may include:

• Threatened preterm labor.
• Severe preeclampsia.
• Significant fetal growth restriction.
• Twin-to-twin transfusion syndrome.
• Vaginal bleeding.
• Preterm premature rupture of membranes.

Hospital monitoring may involve:

• Continuous fetal monitoring.
• Frequent maternal observations.
• Daily fetal surveillance.
• Repeat blood tests.
• Medication administration.

Hospital admission allows rapid intervention if maternal or fetal status deteriorates.

Monitoring for Preterm Labor

Preterm birth occurs more commonly in twin pregnancies.

Healthcare providers assess for symptoms such as:

• Regular contractions.
• Pelvic pressure.
• Lower back pain.
• Vaginal bleeding.
• Increased vaginal discharge.

Women at increased risk may undergo:

• Cervical length monitoring.
• Assessment for uterine activity.
• Additional fetal surveillance.

Prompt identification of preterm labor allows timely treatment, including corticosteroid administration when appropriate.

Determining the Timing of Delivery

One of the primary goals of twin pregnancy monitoring is determining the safest time for delivery.

Delivery timing depends on:

• Chorionicity.
• Maternal health.
• Fetal growth.
• Presence of complications.
• Results of fetal surveillance.

Many uncomplicated twin pregnancies are delivered before 40 weeks because the risks associated with continuing the pregnancy increase later in gestation.

According to professional guidelines:

• Uncomplicated dichorionic twins are often delivered around 37–38 weeks.
• Uncomplicated monochorionic diamniotic twins are frequently delivered around 36–37 weeks.

However, individual recommendations vary.

Warning Signs Requiring Immediate Medical Attention

Women carrying twins should seek urgent medical assessment if they experience:

• Reduced fetal movements.
• Vaginal bleeding.
• Leakage of fluid.
• Severe abdominal pain.
• Regular painful contractions.
• Severe headache.
• Visual disturbances.
• Sudden swelling of the face or hands.
• Shortness of breath.

Prompt evaluation can be lifesaving for both mother and babies.

Myths vs Facts About Twin Pregnancy Monitoring

Myth 1: Every twin pregnancy develops complications.

Fact: Although twin pregnancies are considered higher risk, many women experience healthy pregnancies and deliver healthy babies with appropriate monitoring and prenatal care.

Myth 2: Frequent ultrasounds mean something is wrong.

Fact: Additional ultrasounds are a routine part of twin pregnancy care and help healthcare providers monitor growth, placental function, and fetal well-being.

Myth 3: All twins are delivered very early.

Fact: While twins are at increased risk of preterm birth, many twin pregnancies progress well into the late third trimester before delivery.

Myth 4: If both babies are moving, monitoring tests are unnecessary.

Fact: Fetal movements are important, but formal monitoring tests such as ultrasounds, Doppler studies, NSTs, and BPPs provide additional information about placental function and fetal well-being.

Myth 5: Monochorionic twins and dichorionic twins need the same monitoring schedule.

Fact: Monochorionic twins share a placenta and require more frequent surveillance because they are at risk of complications such as Twin-to-Twin Transfusion Syndrome (TTTS).

Emotional Well-Being During Twin Pregnancy

Twin pregnancy can be physically and emotionally demanding.

Many parents experience:

• Anxiety.
• Fatigue.
• Sleep disturbances.
• Concerns about preterm birth.
• Worries regarding delivery.

Helpful coping strategies may include:

• Attending prenatal education classes.
• Seeking support from family and friends.
• Joining support groups for parents expecting multiples.
• Discussing concerns with healthcare providers.
• Consulting mental health professionals if needed.

Emotional support is an essential component of comprehensive prenatal care.

A Physiotherapist’s Perspective: Focus on Regular Monitoring, Not Fear

As a women’s health physiotherapist, I often reassure parents expecting twins that additional appointments and tests are intended to provide reassurance rather than create worry.

Modern fetal surveillance techniques have dramatically improved outcomes for twin pregnancies.

Attending all scheduled appointments, monitoring symptoms carefully, and maintaining close communication with your healthcare team remain among the most important steps you can take during a twin pregnancy.

Questions You May Want to Ask Your Doctor

Consider asking:

• What type of twins am I carrying?
• How often will I require ultrasound examinations?
• Am I at increased risk of preterm birth?
• Will I need Non-Stress Tests or Biophysical Profiles?
• What symptoms should prompt urgent medical review?
• When is delivery likely to be recommended?

Preparing questions before appointments can help improve understanding and reduce anxiety.

Conclusion

Twin pregnancies require specialized monitoring to identify complications early and optimize outcomes for both mother and babies.

Through frequent assessments, advanced ultrasound surveillance, and individualized care plans, healthcare providers can detect concerns promptly and guide safe pregnancy management.

Although additional monitoring may sometimes feel overwhelming, these assessments provide valuable information that helps support healthy pregnancies and positive birth experiences.

Frequently Asked Questions (FAQs)

1. How often will I need ultrasounds during a twin pregnancy?

The frequency depends on the type of twins and pregnancy complications. Many women undergo ultrasounds every 2 to 4 weeks, while monochorionic twins may require scans every 1 to 2 weeks.

2. What is the most important test during a twin pregnancy?

Ultrasound is considered the cornerstone of twin pregnancy monitoring because it assesses growth, amniotic fluid, placental function, and fetal well-being.

3. Why do monochorionic twins need extra monitoring?

Monochorionic twins share a placenta and are at risk of complications such as Twin-to-Twin Transfusion Syndrome (TTTS), requiring more frequent surveillance.

4. Are Non-Stress Tests necessary in twin pregnancies?

NSTs may be recommended during the third trimester, especially when complications such as hypertension, diabetes, or fetal growth concerns are present.

5. Can twin pregnancies result in healthy babies?

Yes. With regular prenatal care and appropriate monitoring, many women carrying twins deliver healthy babies.

6. When should I seek urgent medical attention during a twin pregnancy?

Seek immediate medical care if you experience reduced fetal movements, vaginal bleeding, leakage of fluid, severe abdominal pain, severe headache, or regular painful contractions.

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Medical Disclaimer!

This article has been reviewed and written under the guidance of our Head Physiotherapist, Dr. Kruti Raj (PT, MUHS,CPT,CMPT). The information shared is intended for educational purposes only and should not be considered a substitute for personalized medical advice, diagnosis, or treatment.

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