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Dr. Harvey Kliman, a research scientist in the Department of Obstetrics, Gynecology, and Reproductive Sciences at Yale School of Medicine, has long advocated for more thorough investigation of placentas after miscarriage. As part of a study published last year, Kliman examined more than 1,200 placentas from previously unexplained miscarriages and stillbirths. His team found that most of the miscarriages were marked by dysmorphic chorionic villi (DCV), a category that includes abnormal placental folds. Kliman’s team also found about a third of unexplained stillbirths were associated with a small placenta.

Every year, there are approximately 5 million pregnancies in the United States. One million of those pregnancies end in miscarriage, and more than 20,000 end in stillbirth. Up to half of these pregnancy losses have unidentified causes. Recent and ongoing research, though, suggests that the placenta may hold the key to understanding and preventing some pregnancy complications, such as preterm birth and maternal and infant mortality. A closer look at the placenta—including its size and function—may have a significant impact on stillbirth rates.

A recent study co-authored by Yale Research Scientist Harvey Kliman, MD, PhD, in the journal of Reproductive Sciences showed that in the pregnancy losses they studied, one-third of previously “uncategorized” stillbirths can be attributed to a small placenta. His team reviewed clinical data and placental pathology for more than 1,200 unexplained pregnancy losses and determined that the number one cause of stillbirth is a small placenta. This article, the most popular Reproductive Sciences article of 2023, has hopefully opened up a door to confirming where these losses are coming from, he said.

Among women of childbearing age, as many as 1 in 4 have trouble either becoming pregnant of carrying a pregnancy to term.

Pregnancy loss can result in anguish as well as grief borne in isolation, as the losses are often written off as unavoidable by the general culture. This pain is magnified when the losses recur. And about half the time, such standard diagnostic measures as placental inspection and/or genetic testing after a miscarriage do not provide a clear explanation—which is all the more distressing for potential parents who often blame themselves. Improved placental assessment may be the answer for these patients.

It was the summer of 2018, and Ann O’Neill was pregnant with her fourth baby — another boy. By all standards, this pregnancy, like her others, was healthy and low risk. On the morning before her due date, she noticed her baby had stopped moving. She didn’t want to be perceived as the “stereotypical, hysterical pregnant woman,” but she headed to the hospital anyway, just to be safe. It was there that a doctor told her her baby no longer had a heartbeat.

Dr. Kliman joins guest host Flora Lichtman to talk about his research, and the importance of studying the placenta as a way to better understand what leads to miscarriage and stillbirth.

On this episode of the Reproductive Sciences podcast, Dr. Shangaris meets with Harvey J. Kliman, MD, PhD (Department of Obstetrics, Gynecology and Reproductive Sciences at Yale University School of Medicine) to discuss the recently published paper titled "Placental Pathology Findings in Unexplained Pregnancy Losses."

Yale researchers published a study last month revealing that over 90 percent of unaccounted pregnancy losses can be explained by placental examination.