Postpartum depression isn't just bad for mothers. It has important consequences for the development of infants.
Studies conducted over the years catalogue many of its effects.
Avoidant and disengaged, depressed mothers do not touch their babies as frequently or with the same affection as nondepressed moms—a deficiency that alone can throw off infant development.
Infants of depressed mothers commonly show cognitive delays, including prolonged time to get used to new information, increased time to detect objects and faces, and low levels of exploration of and engagement with their surroundings.
Infants of depressed mothers also exhibit behavioral problems from preschool through high school. This is the case whether the depression began prenatally or postnatally.
Exactly when the depression begins, however, can have a significant impact on the infant. Typically depression is accompanied by elevated levels of the stress hormone cortisol and decreased levels of the neurotransmitters dopamine and serotonin. Because these agents cross the placenta they make up the biochemical milieu in which the fetus grows. Newborns mimic the abnormal biochemical patterns of their mothers, displaying higher cortisol and lower neurotransmitter levels than the neonates of nondepressed moms.
Along with such biochemical imbalances, infants exposed to depression in utero begin life with a variety of physiologic disturbances. These include abnormal patterns of activity in the frontal lobes of the brain, suggestive of a negative affective style; decreased control over many of the body's internal functions; and disorganized sleep patterns. The babies also perform poorly on tests of newborn alertness.
For infants of mothers who first become depressed after childbirth, the consequences are more a function of the mother's interactive style. But they are no less profound. Among other things, such infants spend less time exploring their environment and are less responsive to stimuli.
Because such patterns can derail social, emotional and cognitive development over the long haul, sensitive intervention is mandatory for both mother and child, contends psychologist Tiffany Field, Ph.D. A pioneer in studying and treating infants of depressed mothers, she has found that skin-to-skin touch can mitigate the effects of maternal depression on infants.
Beginning 20 years ago, while working in a nursery for premature infants and searching for ways to help them grow, Field has found that stimulating the pressure receptors of the body can bring about weight gain. Her lab has grown into the Touch Research Institute at University of Miami, where ongoing studies demonstrate the full physiological and psychological response to massage.
For one thing, massage stimulates the vagus nerve, a cranial nerve that branches to many parts of the body. Stimulation of the vagus nerve slows heart rate, which sets babies up to pay attention to the world around them. It also affects the gastrointestinal tract, leading to more efficient food absorption. In addition, vagal stimulation by massage curbs production of cortisol, which calms infants. They cry less when put down and sleep more.
Massage also enhances the ability of babies to engage in face-to-face interaction with their mother, through which babies learn the basic rules of human social exchange. The responsiveness of babies, in turn, encourages further interaction.
But not just any old massage will do.
Field found that the premies did not gain weight if she just lightly stroked their bodies. It takes an "adequate" amount of pressure-enough to make indentations in the skin as her hand moved across the surface of the infant's body. The indentations had to be deep enough so that the infant's skin color changed slightly, but gentle enough so that it returned to its baseline color before Field removed her hand.
To an unfamiliar eye, such pressure may appear a bit rough. But Field has found it exactly squares with massage practices common in indigenous cultures.
By massaging her infant, a mother both defeats depression in herself and combats its effects on the baby. Massaged infants return the favor with sweet vocalizations and positive affect. They are less restless, less fussy, and faster to sleep. Depressed new mothers come to see their baby more positively and their role as a mother in a new and more positive light.
But they often need interactive coaching to become sensitive to their baby's cues. Field and her coworkers alert the mother to her baby's positive behaviors. They also teach mothers the highly rewarding art of imitation—projecting a smiling face and eliciting the identical response from the baby. Such positive feedback encourages continued cycles of interaction—and that's good for the growth and development of healthy mothers and healthy babies.