Maternal Mental Health: Understanding the Impact on Fetal Development
There is increasing evidence that high levels of stress and depression can affect children long after birth, a major focus of investigations by Catherine Monk, PhD, Professor of Medical Psychology in the Departments of Obstetrics and Gynecology and Psychiatry, and Research Scientist VI at the New York State Psychiatric Institute. Dr. Monk, a clinical psychologist, brings together the fields of psychopathology, developmental neuroscience, and perinatal psychiatry to understand the earliest influences — those that happen in utero — on developmental trajectories of children and how to intervene to prevent mental health problems.
“I straddle two worlds — women’s mental health and child development, with the understanding that children’s brains start developing in utero,” says Dr. Monk. “Much of my work focuses on pregnant and postpartum women, with the goal that when we’re helping a woman with stress, depression, or anxiety, we’re also potentially helping the next generation.”
“There is an intense biological connection between the mother and the fetus, such that the mother’s lifestyle in essence is the fetus’s first environment,” explains Dr. Monk, who directs the Perinatal Pathways Laboratory. “Often now the saying is that the womb is as important as the home in terms of how children develop. We’re understanding that depression is, of course, very much a subjective, psychological experience, but it’s also happening on a biological level. If you’re depressed in pregnancy, these changes in biology amount to an altered in utero environment for the fetus.”
Impact of Distress on the Developing Fetus
In the May 2019 issue of the Annual Review of Clinical Psychology, Dr. Monk and her Columbia colleagues reviewed what is known about the prenatal developmental origins of future psychopathology. “In addition to shared genes and the postnatal environment, a third pathway for the familial inheritance of risk for mental illness is the prenatal environment,” notes Dr. Monk. “Epidemiological and observational clinical data demonstrate that maternal distress — defined broadly to include perceived stress, life events, depression, and anxiety — is related to children’s increased risk for psychopathology. For example, high maternal anxiety is associated with a two-fold increase in the risk of probable mental disorder in children.”
Much of Dr. Monk’s research has centered on identifying the effects of maternal depression, anxiety, and stress before the baby is born, closely following birth, or just a few months afterwards in order to rule out postnatal influences on the developing child. In one study, Dr. Monk tested pregnant women, some of whom had untreated depression, anxiety, or high stress, using the Stroop Color Word Matching Task, an interference task that measures selective attention and cognitive flexibility and is known to make the tester feel pressured and stressed. “The test produces a certain amount of performance anxiety as the computer lets the women know if they are getting the answers wrong,” says Dr. Monk. “The test only lasts five minutes, but it does tell us on a scale of 1 to 10 how stressed the women are. At 8, 9, or 10 we can see that their blood pressure and respiration increase.”
“The women’s blood pressure and respiration changes are a stimulus for the fetuses; some react, and some do not,” continues Dr. Monk. “What we’ve seen is that fetuses of depressed and anxious women are more reactive, and when we look at them at four months, they are also more reactive.”
In another study of newborns, Dr. Monk and colleagues used brain imaging to test resting state functional connectivity between the amygdala, which is involved in fear response and emotions, and the prefrontal cortex. “The fetuses of depressed women showed less connectivity, so their prefrontal cortex was not able to calm down their amygdala,” she says. “The newborns who have less connectivity in this brain circuit had the greater heart rate response as fetuses. So, the emerging story is fetuses whose mothers are depressed or anxious, both in their behavior and their brain connectivity, are more reactive.”
“Epidemiological and observational clinical data demonstrate that maternal distress is related to children’s increased risk for psychopathology.”
— Dr. Catherine Monk
Dr. Monk, as well as other researchers working in this area known as prenatal programming, believe a mother’s biological signals of stress, anxiety, or depression are a way to prepare the fetus for the postnatal environment. “If the mother is very stressed, anxious, or worried, she’s giving signals that it’s a tough world out there,” says Dr. Monk. “These biological signals to which the fetus is adapting may make the baby a more reactive child, and that might actually be beneficial if the world is threatening and dangerous. The problem is if the baby responds to a lot of stimuli and is very alert and reactive to the environment, then at age five or six they can develop in a way that looks like attention deficit hyperactivity disorder. They can’t pay attention and can’t match well to demands. This emphasizes the need to be thinking from a developmental perspective about where all these problems originate and how to prevent them.”
Among the different pathways that Dr. Monk and her colleagues are exploring is the hypothalamic-pituitary-adrenal (HPA) axis and the stress hormone cortisol. “We have looked at a gene in the placenta that codes for an enzyme that deactivates cortisol as it crosses the placenta,” says Dr. Monk. “We found that when women had higher stress, this gene, through epigenetic processes, including methylation, got turned off. If it was highly methylated, then there would be more cortisol crossing into the fetal compartment, and the fetal brain would be exposed potentially to relatively atypical higher levels of cortisol.”
Dr. Monk has also developed an intervention that begins during pregnancy to prevent postpartum depression. “My research and clinical practice are very interconnected and very gratifying,” she adds. “We should be treating women for themselves and also in their transition to parenting. With a prevention focus, we can intervene during pregnancy for the mother and for her future child. We are working with our obstetrics colleagues to identify and treat distress before it becomes significant depression. It’s great to start there, because that’s really the origin of future well-being, of children, and of families.”
Dr. Monk now is putting her research into practice. She is heading up a new initiative in Obstetrics and Gynecology embedding women’s mental health services alongside routine prenatal and postnatal care — greatly expanding access to care by reducing logistical and scheduling challenges. Her team also is leveraging telemedicine to ensure women’s mental health needs are met independent of traveling and scheduling issues. Says Dr. Monk, “We are taking our work, and that of many other researchers, and having it directly inform our clinical mission.”
Monk C, Lugo-Candelas C, Trumpff C. Prenatal developmental origins of future psychopathology: Mechanisms and pathways. Annual Review of Clinical Psychology. 2019 May 7;15:317-44.