It’s really important to look at people’s emotional health on this global scale, says Jeffrey Borenstein, MD, an associate clinical professor of psychiatry at Columbia University.

"Gastrointestinal problems ... can have profound effects on a child's behavior," Dr. Kara Gross Margolis, an associate professor of pediatrics at Columbia University, said in a press release.

John Rowe, a professor of health policy and aging at Columbia University Mailman School of Public Health, predicts that fertility rates will drop even lower in the coming years.

Rita Charon, a Harvard University-trained physician with a Ph.D. in English literature, is the founding chair and professor of medical humanities at the Columbia University Irving Medical Center.