Surveillance And Monitoring of Twin Pregnancies

Twin pregnancies have a higher chance of having high-risk complications. Monitoring and surveillance help to judge and provide appropriate measures to reduce these pregnancy complications.

Ultrasound Surveillance

Ultrasound scanning and monitoring can identify details such as:

  • Accurate gestation date or date of pregnancy.
  • Nuchal translucency assessment to test and measure the nuchal fold thickness.
  • Anatomic survey to check the development of the fetus and detect any physical disorders.
  • Determination of chorionicity to evaluate the number of the placental masses.
  • Placental evaluation to check for any fetal growth restriction or neurodevelopmental impairment.
  • Cervical length assessment evaluates cervical length which checks the risk factor of preterm labour and premature birth.
  • Routine fetal growth evaluates the growth of the fetus and fetal heart activity and rhythm.
  • Pregnancy abnormalities can increase complications.
  • Cervical shortening may increase the risk of premature birth and preterm labour.
  • Amniotic fluid abnormalities can cause pulmonary hypoplasia.

All pregnant women with twins should undergo ultrasound surveillance for the growth assessment of their babies. This ultrasound surveillance must include an anatomic survey and also early determination of chorionicity.

Ultrasound Monitoring for Monochorionic Twins

In the case of monochorionic twins, ultrasound surveillance is required every 2 weeks from the 16th week of pregnancy. This identifies:

  • Monoamnionicity: both fetuses share a single amniotic sac.
  • Conjoined Twins: both babies remain physically connected.
  • Twin Reversed Arterial Perfusion (TRAP) Syndrome: In this case, the cardiac system of one twin is responsible for supplying both twins with blood.
  • Twin-Twin Transfusion Syndrome (TTTS): It occurs when twins share one placenta and a network of blood vessels.
  • Selective Intrauterine Fetal Growth Restriction (IUGR): When one of the identical is normal while the other is significantly smaller in size.
  • Twin Anemia-Polycythemia Sequence (TAPS): It occurs in monochorionic twins when the blood flow between twins is unequal.
  • Single Intrauterine Fetal Demise (IUFD): This occurs when one of the two fetuses dies of various complications.

These all can be identified via ultrasound surveillance and monitoring. Nowadays there are many new technologies for medical treatments for various complications. Early ultrasound evaluation can easily and accurately identify several complications during the first trimester.

Biophysical Profiles and Non-stress Test for Antenatal Surveillance

Weekly biophysical profiles and non-stress tests

  • for monochorionic twins are required at the 32nd week of pregnancy.
  • For dichorionic twins is required at the 34th week of pregnancy.

During twin pregnancies, routine antenatal surveillance is done using a sonographic biophysical profile resulting in a:

  • Low false-positive rates.
  • Low incidence of IUFD or Incidence of Intrauterine Fetal Death.


Twin pregnancies have a higher risk of pregnancy complications. Early knowledge of the type of twin you are pregnant with may clear out or cause more complications. As in the case of Conjoined twins, the risk of complication is highest and sadly many conjoined twins only live for a short while.

The end goal of all this monitoring and surveillance is to help you and your babies have a safe and healthy childbirth and long life. So contact and consult a licensed health care and prenatal care provider.

Request an appointment at Apollo Cradle, DELHI-NCR - Chirag Enclave. Call 1860-500-1066 to book an appointment.

1. Twin Pregnancies: During when are they monitored?

You should perform an ultrasound scan during the 11th to 14th weeks. It is the best time to find out details regarding your twin pregnancies. If you are having conjoined twins then the routine ultrasound during the 7th to 12th weeks will identify it.

2. Do you require a Maternal-Fetal Medicine specialist in case of twin pregnancies?

A Maternal-Fetal Medicine specialist is required only during high-risk pregnancies. Not all twin pregnancies are high-risk.

3. How frequently do you require visiting your doctor in case of twin pregnancies?

In the case of twin pregnancies, you will have to visit prenatal care more frequently. Especially if your twins share the same placenta then you need more frequent visits to prenatal care.

4. How frequently do you need to get an ultrasound scanned in case of twin pregnancies?

You only need ultrasound scans every 4 weeks from the 20th week of gestation, in case you have uncomplicated twin pregnancies. For complicated and high-risk twin pregnancies the doctor and prenatal care provider will offer further scanning.

5. What are the types of twins?

There are three types of twins.
1. Fraternal Twins: Dizygotic Twins happen when two separate eggs are fertilized by two separate sperms. In this case, both babies develop in their separate placentas.
2. Identical Twins: Monozygotic Twins happen when one fertilized egg splits in two and grows two separate embryos. In this case, twins are identical in gender, and blood type and also share physical traits. They may or may not share a placenta in the case of identical twins.
3. Conjoined Twins: This is a rare case that happens in monozygotic twins. When the two embryos only partially separate. Conjoined twins can be connected at different spots and may also share one or more internal organs.

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