New way to size up placentas

YALE (US)—Thousands of pregnancies are lost each year because the placenta is simply too small and the fetus runs out of food and oxygen. Now, researchers have developed a method to gauge placental volume.

With current technology, doctors have been unable to monitor the growth of the placenta, which, like a car’s gas tank, provides fuel for the fetus, says Harvey Kliman, a research scientist in the department of obstetrics, gynecology, and reproductive sciences at Yale University.

He theorized that in much the same way an obstetrician uses ultrasound to follow the growth of the fetus and a pediatrician weighs and measures children to ensure proper growth, the placenta could similarly be monitored.

Because of the placenta’s curved structure, Kliman says perinatologists often find it difficult to measure it without specialized equipment and training.

Kliman and his father, Merwin Kliman, a mathematician and electrical engineer, developed an equation that uses the placenta’s maximal width, height, and thickness.

Kliman then validated the method by comparing the volume predicted by the Estimated Placenta Volume (EPV) equation taken just before delivery to the actual weight of the placenta at the time of delivery.

“In this study, we showed that the equation predicted the actual placental weight with an accuracy of up to 89 percent,” says Kliman. “The method works best during the second and early third trimesters, just when routine ultrasound screening is done on many women in the U.S.”

The team is also collecting EPV data from centers around the world to create the normative curves that doctors can use to determine if the placenta is normal, too small, or even too big.

“I hope that the EPV test becomes routine for pregnant women,” Kliman says.

The results appear in the Aug. 3 issue of the American Journal of Perinatology.

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