A downside to cesareans

Lacking a hormone that promotes bonding.

Expectant mothers around the world are opting in growing numbers for cesarean sections that are not medically necessary. This surgery, developed to save lives, has become the preferred mode of delivery in some countries. But research by Yale child psychiatry professor James E. Swain and his colleagues may give voluntary cesarean patients pause. In an exploratory study, key brain regions of six women who had given birth vaginally were more responsive to their babies, several weeks after delivery, than were those of six counterparts who delivered by elective cesarean.

Each mother listened to three kinds of recordings while her brain was scanned by fMRI: her own baby's cries (during diaper changes), another baby's cries, and white noise. The brains of those who had given birth vaginally showed a consistent pattern of increased activity in regions that direct motivation, emotion regulation, and empathy. The activity was strongest when they heard their own babies. (The work appears in the October Journal of Child Psychology and Psychiatry.)

Swain suspects the reason is oxytocin, the "cuddling hormone" released during vaginal birth (as well as breast-feeding and sex) but not during a cesarean. Oxytocin promotes bonding. But a preliminary look at other data his team is analyzing suggests there may be less of a difference after a few months. Perhaps women who have cesareans catch up later. Most importantly, nobody knows if the difference Swain found affects the child's or mother's well-being.

"We're not saying 'Don't have cesarean sections,'" says Swain. But he hopes his findings will promote research, as well as "a little extra caution" from women and their caregivers regarding elective cesareans. 

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