Pregnant women who are under a lot of stress, feeling depressed or anxious may give birth to babies that weigh less and are smaller than average at midterm.

A new report from the University of Miami School of Medicine reveals cortisol may be one way the mother can transmit her stress to her unborn baby.

“Maternal distress is accompanied by biochemical changes, such as increased cortisol, that can both directly and indirectly affect the fetus,” reports lead researcher Miguel A. Diego, Ph.D. “Cortisol can directly cross through the placenta into the fetus, which could affect fetal development.”

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