Fetal heart rate. Part II: Behavioral correlates

STUDIES IN FETAL BEHAVIOR: REVISITED, RENEWED, AND REIMAGINED

Among the earliest volumes of this monograph series was a report by Lester Sontag and colleagues, of the esteemed Fels Institute, on the heart rate of the human fetus as an expression of the developing nervous system. Here, some 75 years later, we commemorate this work and provide historical and contemporary context on knowledge regarding fetal development, as well as results from our own research. These are based on synchronized monitoring of maternal and fetal parameters assessed between 24 and 36 weeks gestation on 740 maternal-fetal pairs compiled from eight separate longitudinal studies, which commenced in the early 1990s. Data include maternal heart rate, respiratory sinus arrhythmia, and electrodrmal activity and fetal heartrate, motor activity, and their integration. Hierarchical linear modeling of developmental trajectories reveals that the fetus develops in predictable ways consistent with advancing parasympathetic regulation. Findings also include:within-fetus stability (i.e., preservation of rank ordering over time) for heart rate, motor, and coupling measures; a transitional period of decelerating development near 30 weeks gestation; sex differences in fetal heart rate measures but not in most fetal motor activity measures; modest correspondence in fetal neurodevelopment among siblings as compared to unrelated fetuses; and deviations from normative fetal development in fetuses affected by intrauterine growth restriction and other conditions. Maternal parameters also change during this period of gestation and there is evidence that fetal sex and individual variation in fetal neurobehavior influence maternal physio-logical processes and the local intrauterine context. Results are discussed within the framework of neuromaturation, the emergence of individual differences, and the bidirectional nature of the maternal-fetal relationship.We pose a number of open questions for future research. Although the human fetus remains just out of reach, new technologies portend an era of accelerated discovery of the earliest period of development

Neurobehavioral anomalies in neonates with seizures

Neurobehavioral evaluation of the high-risk neonate represents an important advance in early detection of behavioral anomalies which may give rise to later neuropsychological sequelae. In the present study neonates comprising three diagnostic categories (i.e., respiratory distressed, seizure-disordered, normals) were evaluated with the Brazelton Neonatal Behavior Assessment Scale (BNBAS) to determine the extent to which differences in neurobehavioral organization could be detected with the scale, and how they were related to diagnostic classification. Average conceptional age at testing for the three groups was within the range usually considered full term: e.g., 38.81 weeks (respiratory distressed), 40.18 weeks (normal healthy) and 42.54 weeks (seizure disorder). Infants who had been diagnosed with neonatal seizures exhibited consistently less optimal behavior than did either of the other two groups. Infants with respiratory distress and normal controls did not differ significantly on most summary measures of neurobehavioral organization scored with the BNBAS. The study offers support for the discriminative validity of the BNBAS and its potential usefulness in the assessment of clinically ill newborns.