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Abstract

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 electrodermal activity and fetal heart rate, 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 physiological 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.

Assessment of autonomic function in the late term fetus: The effects of sex and state

“…We did not find that GA was correlated with FHR and FHRV, perhaps due to low power and the small range for gestational age (36-39 weeks). Despite this, our results suggest that males exhibit the more mature pattern as they have lower FHR and higher FHRV than females (DiPietro et al, 2015). Similarly, FHRV was reported to be less complex for near-term male fetuses compared to female fetuses, indicating a more mature nervous system that functions more autonomously (Bernardes et al, 2008).…”

“…In a larger study, DiPietro, Costigan, & Voegtline (2015) collected data from 740 fetuses and found that in the late term fetus, males show a more mature pattern of autonomic function than females.…”

Prenatal maternal psychological distress and fetal developmental trajectories: associations with infant temperament

“…A primary advantage to studying neurobehavioral development in utero is that associations between maternal psychological distress and developmental outcomes can be examined prior to postpartum influences. Measures of fetal brain and neurobehavioral development are more proximal and likely more accurate indicators of fetal exposures (DiPietro, Costigan, & Voegtline, 2015; Sandman, 2015). Very recent advances in fetal functional magnetic resonance imaging have enabled direct observation of brain development during the prenatal period (Thomason et al, 2018; van den Heuvel & Thomason, 2016).…”

“…Very recent advances in fetal functional magnetic resonance imaging have enabled direct observation of brain development during the prenatal period (Thomason et al, 2018; van den Heuvel & Thomason, 2016). However, there is a long-standing tradition of assessment of fetal behavior as a noninvasive method of measuring neurodevelopment (see DiPietro et al, 2015). Fetal heart rate (FHR) and fetal movement parameters are established indices of central and autonomic nervous system maturation and function which demonstrate continuity with postnatal outcomes (DiPietro et al, 2015, 2010; Nijhuis, Swaab, Heuser, Brosens, & Eskes, 2003; Sandman, 2015).…”

Impact of maternal prenatal smoking on fetal to infant neurobehavioral development

“…In just 266 days, a single fertilized cell develops into a sentient human newborn infant” (DiPietro, 2010). Further, “there is no other period in development in which the proximal environment is so physiologically entangled” with the offspring (DiPietro, Costigan, & Voegtline, 2015). Ongoing improvements in ultrasound technology and fetal monitoring have allowed understanding of fetal development to progress from delineating structural and organ development to assessing patterns of fetal movements and fetal heart rate (FHR) to elucidating fetal state and neurobehavior (DiPietro et al, 2010; Groome, Bentz, & Singh, 1995; Nijhuis, Martin, & Prechtl, 1984; Nijhuis, Prechtl, Martin, & Bots, 1982).…”