Twin Prenatal Care: Preterm Birth and Fetal Growth Restriction

Posted On: August 9, 2022 By Andrei Rebarber, MD

Twin pregnancies often introduce more complications that singleton pregnancies, but fortunately our maternal fetal medicine specialists have specific tests and healthcare protocols to identify potential risks and create treatment plans to prevent them from causing complications.

Two common risks during twin pregnancy are preterm birth and fetal growth restrictions, which Dr. Andrei Rebarber discussed with Dr. Nathan Fox in a recent episode of the Healthful Woman podcast.

What is Twin Pregnancy Preterm Birth?

Preterm birth is generally defined as delivering between 20 and 36 weeks. Your due date is calculated as 40 weeks from the time of the first day of your last menstrual period, and most singleton pregnancies are expected to deliver near that time. For multiple fetuses, however, they often deliver preterm, with twins expected to be delivered around 36-37 weeks gestation and triplets around 33-34 weeks gestation.

Dr. Rebarber explains that on average, 50% of twin pregnancies deliver preterm, which is before 37 weeks. This can be due to various biological factors such as when the uterus has simply reached the point where it cannot stretch anymore or due to infection and/or bleeding. 70% of preterm twin births will go into preterm labor due to one of these factors. Medically indicated preterm birth accounts for 30-40% of preterm deliveries of twins and is often performed in order to save the mother’s life or in cases where the babies are in danger should the pregnancy continue.

Treatment Options for Twin Preterm Birth

Because the majority of preterm birth cases for twins are due to the body initiating preterm contractions and cervix dilation, there’s typically nothing doctors can do to guarantee that people at risk for preterm birth can carry to full term. Instead, Dr. Rebarber says that “we have various tools and treatments that we may be able to prolong gestation in situations where just buying time allows us to have simple interventions such as steroids to help the lungs mature, magnesium sulfate, etc. . . . in some situations, that allow for prolongation of gestation, which would improve outcomes.”

This means that although it may not be possible to avoid a preterm birth, your maternal fetal medicine specialist has many screenings and treatment options to give your twins the best circumstances for their delivery and later on in life.

What is Fetal Growth Restriction?

Growth restriction in twin pregnancies refers to a condition in which one or both of the fetuses are not growing well. Fetal growth restriction is measured with a few key metrics: femur length, head circumference, and belly size. In addition to being a risk factor for morbidity on its own, growth restriction can also increase the risk for preterm birth.

If doctors discover an issue with fetal growth rate during pregnancy, the next step will be to take a battery of tests to get more information about the development of each fetus, especially the one in question. This includes ultrasounds, which can determine the following: blood flow in the umbilical cord, placental function, and fetal brain activity, according to Dr. Rebarber. This information allows doctors to make a difficult recommendation: “Is the baby better in than out or out than in?” These tests help determine when to deliver the babies so both have the best outcomes possible.

Treatments for Fetal Growth Restriction

When our maternal fetal medicine specialists notice an abnormality in the growth rate of one or both twins, there are a number of steps we take after identifying exactly what stage of development the fetuses are in as well as to what degree the growth has been restricted.

One thing we begin doing at 32 weeks or so are what are called biophysical profiles on a weekly basis. This establishes a risk factor profile for stillbirth to help inform doctors about the best time to deliver. The eventual treatment for fetal growth restriction is giving birth, it’s just the timing will have to be monitored carefully for the best results.

More Information about Twin Pregnancies and Delivery

At Carnegie Imaging for Women, we provide the highest standard of care for ultrasound imaging and testing to help determine many aspects of pregnancy care from the number of fetuses you’re carrying to how they develop throughout gestation. To learn more about our specialty services for twin pregnancies or to learn about high-risk pregnancies in general, we invite you to subscribe to the Healthful Woman podcast or come in for an appointment today.

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

Comments are closed.