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Placenta abnormalities could be the reason for miscarriages, study suggests

The team looked at a series of 1,527 single-child pregnancies that ended in miscarriage - here’s what they found

Faiza Saqib
Tuesday 19 September 2023 16:39 BST

A new study has found that placenta abnormalities could be the reason for miscarriages.

In the United States, there are approximately 5 million pregnancies per year with 1 million ending in a miscarriage and over 20,000 ending in stillbirth, according to a paper published in the journal Reproductive Sciences.

“To have a pregnancy loss is a tragedy. To be told there is no explanation adds tremendous pain for these loss families,” said senior author of the paper and research scientist at Yale School of Medicine, Dr Harvey Kliman

“Our goal was to expand the current classification systems to decrease the number of cases that remained unspecified.”

For the study, researchers worked to create a classification system for miscarriages based on a test that examines a sample of the body’s tissues – known as pathologic examination.

The team looked at a series of 1,527 single-child pregnancies that ended in miscarriage, and the data was then sent to Yale for evaluation.

After excluding cases without adequate material for examination, 1,256 placentas from 922 patients were examined.

Of these, 70 per cent were miscarriages and 30 per cent were stillbirths.

By adding the explicit categories of “placenta with abnormal development” (dysmorphic placentas) and “small placenta” (a placenta less than the 10th percentile for gestational age) to other incidents such as cord accident, abruption, thrombotic, and infection – researchers were able to determine the results of 91.6 per cent of the pregnancies, including 88.5 per cent of the miscarriages and 98.7 per cent of the stillbirths.

The most common results for unexplained miscarriages were dysmorphic placentas (placenta with abnormal development) which was around 86.2 per cent.

For stillbirths, there was 33.9 per cent due to a small placenta.

“This work suggests that the over 7,000 small placentas per year associated with stillbirths could have been detected in utero — flagging those pregnancies as high risk prior to the loss,” said Dr Kliman.

“Likewise, the identification of dysmorphic placentas may be one way to potentially identify genetic abnormalities in the almost 1 million miscarriages that occur in our country every year.”

He said having a definite explanation “for a pregnancy loss helps the family understand that their loss was not their fault, allows them to start the healing process, and, when possible, prevent similar losses — especially stillbirths — from occurring in the future.”

When asked what the most effective way might be to prevent stillbirths, Dr Kliman responded, “Measure the placenta!”

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