Previous research has shown that a pregnant woman’s reaction to stress can pass through the placenta to negatively impact the fetus in ways that manifest after birth, such as low birth weight, poor brain development, and greater vulnerability to illness.
“We were curious about whether maternal behavior could buffer the child against the effects of maternal depression, and if this buffering could be observed at the level of the infant’s epigenome,” said assistant professor Dr. Elisabeth Conradt in the Department of Psychology at the University of Utah.
“Many mothers struggle with depression but interact quite sensitively with their infants. In these instances, the mother may be turning on certain genes that we think allow infants to manage stress in adaptive ways.”
Conradt and her team worked with 128 infants of women with self-reported symptoms of depression and obtained DNA from the infants through cheek swabs and cortisol levels from their saliva.
The infant-mother pairs participated in three two-minute face-to-face play episodes. The first episode required normal play between mother and infant, the second episode required that the mothers be unresponsive to their infants and the third episode was a reunion episode where mothers were allowed to interact again.
Maternal sensitivity was recorded every 30 seconds and assessed using four scales.
- Maternal acceptance: Willingness and ability of the mother to follow her infant’s lead.
- Demandingness: the degree to which the mother required her infant to behave a certain way.
- Responsiveness: Both the mother’s awareness of her infant’s signals and her response to them, regardless of the appropriateness of response.
- Appropriate touch: The mother’s ability to touch her infant in a gentle and affectionate manner.
The researchers took a pre-stress cortisol sample from each infant prior to entering the lab and two post-stress samples after the unresponsive play episode and after the reunion play episode. A cheek swab for DNA was taken after the second play episode.
The findings show that greater levels of maternal sensitivity were associated with lower levels of cortisol. While there were no differences in DNA methylation among infants whose mothers scored high on sensitivity, infants whose mothers were both less sensitive and had high depressive symptoms had higher levels of methylation and more cortisol.
Furthermore, depressed moms who were more responsive and engaged in more appropriate touch during face-to-face play had infants with less DNA methylation compared to depressed moms who were also insensitive.
Therefore, having a sensitive, affectionate mother appears to buffer babies from the exposure of the mom’s depressive symptoms.
The researchers are currently repeating and extending this study with first-time pregnant women in Utah to better understand whether certain parenting behaviors can buffer the infant to the effects of prenatal exposure to stress and depression.
“We are excited about the possibility that this research may lead to specific ways one can effectively intervene with pregnant women at risk for postpartum depression,” Conradt said.
The findings are published in the journal Child Development.
Source: University of Utah