We are all products of a life before birth, and more specifically, a life before we can remember. Prenatal life in the human remains something of an enigma, partly because it is often perceived as a transitional state somewhere on the boundary between human and animal existence. The human fetus lives in a world more characteristic of aquatic mammals than human beings, and yet from these ontogenetically humble be■ginnings emerges an organism endowed with all the capacities for uniquely human functioning. It is, therefore, fetal life, in comparison to all other stages of human development, that marks our biological link to the animal kingdom.
Although scientific interest in prenatal and early postnatal life has existed for centuries, it is only within the last few decades that a concerted and systematic scientific effort toward understanding life's earliest period has been undertaken. Ironically, although pregnancy, childbirth, and infant development have traditionally been thought of as the domain of obstetrics, pediatrics, and general medical science, it is behavioral science and psychology that have made far-reaching discoveries in these areas.
Psychological science has probably had the greatest impact on the changing views of early human development, and specifically, our views on how the environment affects the unborn and newborn infant. Psychological science can take credit for informing the clinical, scientific, and lay communities about the capabilities of the young human organism and the envionment that shapes behavior throughout life. We can now begin to focus on the complex problems that continue to exist regarding how physical and environmental variables interact to produce the unique capabilities of human beings.
One approach to this problem has been to study infant development, and more recently, prenatal development, in order to understand the continuity of early life and its impact on later functioning. Ironically, the earliest behavioral and psychophysiological studies of the human fetus were conducted by Lester Sontag of the Fels Research Institute from the 1930s to the 1970s. Few outside the field of infant development know that this research was conducted by a psychologist. More recently, we have discovered a number of interesting facts about the human infant and fetus. In particular, we now know that the human infant can see on the first day of life, a notion that only became accepted during our lifetime. We also know that the human fetus is responsive to stimulation, and even shows rudimentary signs of learning and memory. This is in contrast to the preexisting view that the human fetus was simply a passive immature organism with few, if any, sensory capabilities.
One of the greatest ironies in high-risk infancy research has been the success of obstetric medicine and intensive care units in saving the lives of thousands of infants who would have died a generation ago. Today, it is not uncommon for an infant to be born at 26 to 28 weeks and survive with relatively few heroic medical interventions. These advances in life-saving technologies for medical and biomedical research have been lauded for decades, and rightly so. The paradox, however, is that although biomedical science and clinical medicine have been enormously successful in saving the lives of these small and very fragile human beings, society has been burdened by the dramatic increase in psychological and behavioral morbidity. Thus, laws such as the Individuals With Disabilities Education Act are responses to the increase in the number of children with disabilities who require special intervention. Many of these children would not have lived had it not been for these biomedical advances. As a society, we believe that saving lives is ultimately important, and my feelings do not vary with societal philosophy. But we have burdened ourselves economically, socially, and emotionally by having a large group of children who now require special care from birth throughout childhood, and in many cases, throughout adult life. So what are we to do, and what role do psychological science and behavioral intervention play in reducing the rate of behavioral and psychological morbidity among this very high-risk group of individuals? The answers may come principally from psychological research.
Within the past few years, an enormous scientific interest has emerged regarding psychobiological development in the huan fetus. This interest capitalizes on a steadily improving sophistication in biobehavioral research methodology over the past 4 decades. From the early application of Doppler ultrasound to the latest advances in fetal surgery, there can be no doubt that the scientific study of the human fetus is a field whose time has come. What makes the study of fetal development so interesting is its promise for enriching our knowledge about one of life's most mysterious phases: the prenatal period, memories of which have long passed into the most primordial reaches of our collective unconscious.
These uncharted paths remain a curiosity and are now being explored through scientific inquiry. There are now numerous examples of the remarkable cognitive, memory, and attentional capabilities of the human infant, and in some instances, of the human fetus. Most, if not virtually all, of these discoveries have been made by psychologists and behavioral scientists. For example, sophisticated behavioral research indicates that infants have remarkable memories for contingencies over relatively long periods of time, such as weeks and months. Psychological research has found that newborn infants prefer animate versus inanimate objects and respond differentially to an intact human face versus a distorted human face. Other research has shown the remarkable ability of the 1- to 2-day-old neonate to imitate facial gestures, an ability that would have been thought of as hearsay only a couple of generations ago. More recently, it has been discovered that the human fetus remembers the maternal voice and actually prefers the maternal voice postnatally when it has been heard prenatally. All of these studies suggest that environmental contingencies play an important role in early human development, but moreover, that the human infant and, by extension, the human fetus, is 'cognitively and perceptually' prepared for certain kinds of sensory experiences. These findings raise numerous questions about how to best arrange environments that maximize the inborn preparedness and capability of the young human organism.
Risk research is defined in developmental psychology as the study of psychological phenomena in groups that have a high probability of developing behavioral disorders. Traditionally, this has included high-risk research with infants, primarily those born too small or too soon (e.g., low birth weight and prematurity). However, high-risk research has also included infants who have other clinical disorders related to neurological integrity and maturation. Contemporary thinking in both medical and psychological research puts forth the notion that many early developmental problems have their etiology during the perinatal or prenatal period. In fact, most medical authorities now believe that a number of clinical conditions observed in the newborn infant and young child have a prenatal origin. Due to the link between pre- and perinatal compromise (risk) and behavioral development, we have introduced the term behavioral perinatology as an umbrella for conceptualizing research and theory related to this very dynamic period of life.
Imaging technologies in biomedical research and clinical practice have found their way into research and clinical practice in psychology and, more specifically, into clinical neuropsychology. For example, it is now customary for clinical neuropsychological studies to include results from PET scans, CT scans, and MRI findings. These technologies are also used in obstetric medicine and in research on prenatal brain behavior relationships. The ability to visualze structures within the human brain during prenatal life opens vast possibilities for the study of basic neuropsychological processes and those related to impairment in neurological development. For illustration purposes I present Figure 1, which is an image of the Circle of Willis in a 26-week-old fetus. The Circle of Willis is a group of arteries that form a circle within the human brain and carry oxygenated blood to all the major lobes of the cerebral hemispheres. The ability to visualize these arteries and to measure the rate of blood flow during gestation is a major technological advance. Our laboratory is currently studying regional distribution of blood flow in relation to fetal movement throughout the third trimester of gestation. We find that fetal cerebral blood flow and behavior are consistently linked during gestation. We believe that the study of prenatal brain-behavior relationships lays the foundation for early postnatal studies of neurological and neuropsychological development. These are exciting times for research into the origins of cerebral organization and the manifestation of cognitive ability.
Other intriguing findings from infant research include the discovery of sexual dimorphism in stress responsivity. We also now know that stressors have a particular effect upon infant responses and that males and females vary in their behavioral and physiologic responses during the neonatal and prenatal periods. Moreover, it has been found that ethnic groups also differ in their responsiveness to handling, stress, and other kinds of stimulation. Perhaps the most remarkable finding in this area pertains to prenatal behavioral profiles that differentiate infants from varied ethnic groups.
Some years ago, in a discussion with one of my neonatologist colleagues, we asked each other why we had decided to study early infant development. I stated that I had found the field intriguing and that the opportunity to learn how physiologic and behavioral systems work together was part of the reason I chose this field of endeavor. My neonatologist colleague responded, 'This is where the action is.' I continue to believe that the study of early infancy and prenatal life remains 'where the action is' in early human development.
As a clinician, one is always concerned with how to ameliorate or mitigate clinical conditions that place the individual at risk for compromised development. This philosophy is relevant to the study of hih-risk infancy and, by extension, high-risk fetal development. Currently, there are a few psychological interventions that appear to be promising with high-risk infants and fetuses. These involve, primarily, two approaches. The first is directed toward the family, and, specifically, to the parents. The basis for this approach is fundamentally grounded in our understanding of how emotions affect behavior and, secondarily, in how social interaction mitigates certain medically high-risk conditions. Thus, much of the work that is done with very sick infants who reside in neonatal intensive care units, over and above medical care itself, involves improving the social and emotional support that parents provide to their sick child. A second approach is a much more formalized behavioral intervention approach. It is based on the contingencies of reinforcement, which basically provides for the acquisition, maintenance, and extinction of desired or undesirable behaviors. In dramatic form, behavioral techniques have been used with terminally ill infants having disorders related to breathing and oxygen exchange. In some cases, these interventions have prolonged life using aversive conditioning to stimulate the infant to breathe when its oxygen level has lowered to a critical point.
Although experimental, the promise of behavioral intervention with the sick human newborn and the human fetus is on the horizon. We fully expect that within the next decade behavioral intervention techniques will be used routinely to ameliorate infant high-risk clinical conditions and to accentuate and enhance normative behavioral and cognitive development.
A result of behavioral perinatology's emergence as a subdiscipline is the need for a new generation of scientists trained to understand the intricacies of maternal-fetal health and the complexity of behavioral and psychological development. Thus, we have initiated a number of training programs at the predoctoral and postdoctoral levels for psychologically and medically trained students. It is believed that fostering such interdisciplinary cross-fertilization will allow the scientific and clinical communities to prepare a generation of neurobehavioral and clinical scientists with well-rounded behavioral and biomedical knowledge in order to tackle the vexing problems of normal and abnormal human development.