August 4, 2009
Preventing Late-Term Pregnancy Loss
Fetal death, or intrauterine fetal demise (IUFD), caused by an under-sized placenta, affects 30,000 women in the U.S. each year.
Technological limits currently prevent doctors from monitoring the growth of the placenta, the source of nourishment for the fetus. "The placenta can be so small that the fetus literally runs out of food and oxygen and dies," lead author Harvey J. Kliman, M.D., a research scientist in the Yale University Medical School Department of Obstetrics, Gynecology and Reproductive Sciences was quoted as saying.
Kliman noted that many late-term pregnancy losses were associated with very small placentas. He theorized that the growth of the placenta could be monitored in much the same way an obstetrician uses ultrasound to follow the growth of the fetus.
When Kliman asked perinatologists why they did not measure the placenta when performing routine ultrasounds, the answer was always the same: the placenta is a curved structure and is too difficult to measure. Measuring placental volume would require very expensive machinery, specialized training and more time.
With the help of his father, mathematician and electrical engineer Merwin Kliman, Harvey Kliman developed an equation to compute the maximal width, height and thickness of the placenta. Kliman and his team 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," said 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."
In addition to validating the equation, the team is also collecting EPV data from centers around the world to create normative curves doctors can use to determine if the placenta is normal, too small or even too big. Kliman expressed his hope that ". . . the EPV test becomes routine for pregnant women."
SOURCE: American Journal of Perinatology, August 3, 2009