Spontaneous motor activity in the perinatal infant before and after birth: stability in individual differences.

This study was undertaken to determine if a relationship existed between the duration of spontaneous general movements before and after birth. Twenty-two infants were examined three times as fetuses between 38 and 40 weeks gestational age and three times as neonates between 2 and 4 weeks postnatal age. Motor activity level during active sleep periods was quantified by direct sonographic visualization for fetuses and by videotaped images of trunk movement for neonates. We found that both fetuses and neonates exhibited stable individual differences in motor activity level. In addition, infants who moved at a certain rate as fetuses generally moved at the same relative rate as neonates up to 4-weeks postnatal age. Our findings suggested that individual differences in motor activity level in the 1st month following birth probably arise during fetal life.

Temporal stability in the distribution of behavioral states for individual human fetuses.

Although behavioral state analyses have been useful in differentiating between groups of normal and at-risk fetuses, the large between-subject differences in the percent time spent in the various behavioral states poses a major obstacle in identifying abnormal neurological functioning in individual fetuses. Does this variability represent a true difference in state organization between fetuses, or does it simply reflect individual fluctuations in state control at the time of observation? To answer this question, we examined each of 33 human fetuses for 4 h on three separate days between 38 and 40 weeks gestation. The percent time spent in each behavioral state and in transition and insertion periods was determined for each of the three 4-h study sessions, and within-subject analysis of variance was performed to obtain an objective measure of state profile consistency for each fetus. We found that, on the average, fetuses exhibited remarkable within-subject consistency in their state profiles. However, even among this group of low-risk fetuses, there were significant differences in the degree of state organization achieved by individual fetuses. These findings, which indicate the existence of a well-developed central nervous system before birth, suggest that individual differences in the consistency of behavioral state profiles may be indexing important between-subject differences in neurological development.

Similarities and differences in behavioral state organization during sleep periods in the perinatal infant before and after birth.

The purpose of this study was to determine the degree of consistency in behavioral state organization for 30 low-risk human participants examined as fetuses at 38-40 weeks gestation and again as neonates at approximately 2 weeks postnatal age. Behavioral states were assigned similarly for fetuses and neonates in terms of heart rate pattern and the presence or absence of eye and gross body movements. We found that the time spent in a sleep period was distributed among quiet sleep (QS), active sleep (AS), and indeterminate states in virtually identical proportions for fetuses and neonates. However, the only within-subject consistency between the fetal and neonatal periods was in the duration of complete QS epochs. Fetuses made fewer transitions between QS and AS, but neonates had shorter and more structured AS-->QS transitions. These findings suggest that, whereas central nervous system processes governing QS do not change appreciably, the control of AS undergoes significant changes in the 4 weeks spanning the fetal and neonatal periods. We believe that the duration of enclosed QS epochs provides the only stable measure of behavioral state development between the prenatal and postnatal periods.

Maternal anxiety during pregnancy: effect on fetal behavior at 38 to 40 weeks of gestation.

The purpose of this study was to determine if there is a relationship between fetal behavior and maternal anxiety during pregnancy. The study population consisted of 18 uncomplicated human pregnancies at 38 to 40 weeks gestation. Maternal anxiety was assessed one time using Spielberger's State-Trait Anxiety Inventory. After an overnight fast, each mother was given a standard meal on arrival to the fetal testing unit. Each fetus was examined for 4 hours using heart rate monitoring and real-time sonography. Fetal behavioral states were assigned based on heart rate pattern and the presence or absence of eye and gross body movements. We found that, compared with fetuses of mothers with low trait anxiety scores, fetuses of mothers with relatively high trait anxiety scores spent significantly more time in quiet sleep and exhibited less gross body movement when in active sleep. The results of this pilot study raise the possibility that maternal anxiety during pregnancy may have a significant effect on fetal behavior.