Why Moms-to-Be May Want to Ask for Extra Ultrasound Scan

In a new British study, researchers gave women an additional scan at 36 weeks. Here’s what they found.

by Lara DeSanto Health Writer

Many moms-to-be count down the days until their next ultrasound, anxious to check in on their pregnancy and see how their little one is doing. But because ultrasounds aren’t recommended unless medically necessary, most healthy women only receive two scans during pregnancy, one in the first trimester and one in the second. But new research could change that, resulting in a third scan later in pregnancy that could help prevent a key complication that affects 3-4% of all pregnancies, per the American Journal of Ob/Gyn.

A new British study found that giving women a 36-week scan could help prevent undiagnosed breech births, which can be dangerous for both mom and baby. It is, however, important to note that a breech presentation can occur after a 36-week scan because some babies have unstable lie, meaning they change positions easily—even after 36 weeks. Typically, a breech presentation can be diagnosed by Leopold maneuvers and then confirmed by ultrasound. In the event of a breech, a decision can be made whether to try external version or plan for c-section.

A breeched delivery could be dangerous for both mom and baby, so there are some things you should know in order to make a sound decision for delivery.

What does it mean when your baby is breech?

Breech presentation is when the baby is in a feet- or butt-down position prior to birth — ideally, babies are in a head-down position, which makes vaginal birth easier and less risky, according to the American College of Obstetricians and Gynecologists (ACOG). For example, if a breech baby is delivered vaginally, it may lead to less severe yet still scary issues such as a prolapsed umbilical cord (when the umbilical cord drops into the vagina ahead of the baby, which means it could become compressed and cut off oxygen and other nutrients to the baby), or the baby’s head or shoulders could get stuck in the mom’s pelvis, which are serious complications that can lead to infant morbidity and mortality. Typically, breech presentation is diagnosed a few weeks before the due date — a health care provider places their hands on the mom’s lower belly to feel where the baby’s head, back, and buttocks are. But sometimes, breech babies go undetected.

To wit: In the study, published in PLOS Medicine by researchers at the University of Cambridge, 3,869 women in England who were pregnant for the first time received screening ultrasounds at 36 weeks of pregnancy—and 179 (or 4.6%) were diagnosed with breech presentation during these scans.

Of the women who did find out their baby was in breech position, more than half had not been suspected of this before the ultrasound. Getting the breech diagnosis at 36 weeks then allowed the women to choose to have health care professionals attempt to turn their baby in a move called external cephalic version—basically, your doc applies pressure to your abdomen and tries to move the baby into the right position from the outside). If it didn’t work, or if the women opted not to have the procedure, then a cesarean section was planned. None of the 179 women chose to have a vaginal breech birth, which has a higher risk of complications — especially in first pregnancies such as these.

Far-reaching benefits

Researchers estimated that this extra routine scan at 36 weeks could prevent 15,000 undiagnosed breech presentations per year across the U.K. They also estimated that they could prevent more than 4,000 cesarean sections and 7-8 baby deaths per year. In the U.S., where the population is nearly 5 times higher than in the U.K, these numbers would likely grow dramatically.

The researchers argued that performing these scans could be cost-saving to the U.K. if the scans could be done for under 12.90 pounds (16.83 dollars) — more research would need to be done to see how this practice could also be applied in the U.S.

"Whether the health improvements are enough to justify the increased cost of ultrasound screening is still uncertain, mainly because the cost of ultrasound screening for presentation alone is unknown," the study authors said. "If ultrasound screening could be provided at low cost, for example by making it a part of a standard [prenatal] appointment, routinely offering ultrasound screening could well represent a good use of [National Health Service] resources."

Lara DeSanto
Meet Our Writer
Lara DeSanto

Lara is a former digital editor for HealthCentral, covering Sexual Health, Digestive Health, Head and Neck Cancer, and Gynecologic Cancers. She continues to contribute to HealthCentral while she works towards her masters in marriage and family therapy and art therapy. In a past life, she worked as the patient education editor at the American College of OB-GYNs and as a news writer/editor at WTOP.com.