After most pregnancies, the placenta is thrown out, having done its job of nourishing and supporting the developing baby.
But a new study raises the possibility that analyzing the placenta after birth may provide clues to a child’s risk for developing autism. The study, which analyzed placentas from 217 births, found that in families at high genetic risk for having an autistic child, placentas were significantly more likely to have abnormal folds and creases.
“It’s quite stark,” said Dr. Cheryl K. Walker, an obstetrician-gynecologist at the Mind Institute at UC Davis, and a co-author of the study, published in the journal Biological Psychiatry. “Placentas from babies at risk for autism, clearly there’s something quite different about them.”
Researchers will not know until at least next year how many of the children, who are between 2 and 5, whose placentas were studied will be found to have autism. Experts said, however, that if researchers find that children with autism had more placental folds, called trophoblast inclusions, visible after birth, the condition could become an early indicator or biomarker for babies at high risk for the disorder.
The research potentially marks a new frontier, not only for autism, but also for the significance of the placenta, long considered an after-birth afterthought. Now, only 10 to 15 percent of placentas are analyzed, usually after pregnancy complications or a newborn’s death.
Dr. Harvey J. Kliman, a research scientist at the Yale School of Medicine and lead author of the study, said the placenta had typically been given such little respect in the medical community that wanting to study it was considered equivalent to someone in the Navy wanting to scrub ships’ toilets with a toothbrush. But he became fascinated with placentas and noticed that inclusions often occurred with births involving problematic outcomes, usually genetic disorders.
He also noticed that “the more trophoblast inclusions you have, the more severe the abnormality.”
More than two-thirds of the low-risk placentas had no inclusions, and none had more than two. But 77 high-risk placentas had inclusions, 48 of them had two or more, including 16 with between five and 15 inclusions.
Kliman calls inclusions a “check-engine light, a marker of: ‘Something’s wrong, but I don’t know what it is.’”
By Pam Belluck