Study Sheds Light On How Moms Soothe Their Distressed Babies

How is it that mothers can soothe their distressed infants? A team of researchers has shed light on this unique process and how it can possibly be improved in mothers with postpartum depression.

There's no denying that moms have that special capability to soothe their babies when they're distressed. However, the mechanisms behind it still aren't well understood, York University noted in a news release.

"Decades of evidence show that mothers provide emotional scaffolding to regulate their infants during moments of distress and that postpartum depression (PPD) can significantly disrupt this process," the authors of the new study, published in the Journal of Psychopathology and Clinical Science, wrote.

"However, it is not known how mothers' soothing signals are transmitted to their baby, how postpartum depression disrupts this process, or if treating depressed mothers can alter these signals," the study's lead author, John Krzeczkowski of York University, said in the news release.

For their work, the researchers looked at 32 "healthy" mother-infant pairs (the control group) and 26 pairs that were affected by PPD within a year of giving birth. During the study, they observed the pairs in three phases, during which the mothers' and babies' heart rate variability were monitored. Heart rate variability is said to be a "known indicator of emotional state," the university noted.

In the first phase (play), the mothers were able to play with their children normally. But in the second phase (still-face), they couldn't touch to talk to their babies, and they had to maintain eye contact while keeping a poker face. As for the third one, it was a reunion phase when they could re-engage with their "now distressed" babies just like they did during the first phase.

It was in the third phase that the researchers looked for synchrony in the mothers' and babies' signals.

They found that the heart rate changes of the mothers in the healthy group actually influenced those of the infants, implying that the mothers were leading the "soothing dance." In the PPD group, on the other hand, the infants were the ones leading.

The researchers conducted the tests twice. The first one was the baseline while the second one was the follow-up after nine weeks.

In between them, the mothers in the PPD group received nine weeks of group cognitive behavioral therapy (CBT). Interestingly, after the treatment, results showed that the PPD mothers were already leading the dance just like the mothers in the healthy group.

"(T)he same pattern was observed in both groups at follow-up," the researchers wrote. "This study provides novel evidence for a mechanism that may explain how mothers actively transmit regulatory support to their distressed infants in real-time."

Since the study was observational in design, it can't "conclusively" say that it was the CBD treatment that led to the change, Krzeczkowski clarified. That said, it may be a contributing factor.

"Our goal is to ensure that more people can get treatment for PPD when they need it," Krzeczkowski said in the news release. "We hope that by conducting future studies that can show causality, it can increase the idea that these programs can benefit them."