Yoshinori Kuwabara

Oxytocin levels in maternal and fetal plasma, amniotic fluid, and neonatal plasma and urine

SummaryOxytocin was measured in maternal and fetal plasma, amniotic fluid and neonatal plasma and urine using a specific radioimmunoassay, following extraction procedures with Florisil. Maternal oxytocin levels rose progressively with advancing gestation, but there were no significant differences between oxytocin levels around the onset of labor. No diurnal rhythm of oxytocin was evident in maternal plasma during the third trimester. Maternal and umbilical plasma oxytocin levels at spontaneous delivery were significantly higher than those at elective cesarean section. Maternal oxytocin levels in four cases of post-term delivery were lower than those during normal late pregnancy; all four cases exprerienced uterine inertia. All amniotic fluid samples had detectable oxytocin levels and there were no significant differences between oxytocin levels in the second trimester and those in the third trimester. Oxytocin levels in neonatal urine were higher than levels in amniotic fluid and lower than in the umbilical artery. Neonatal plasma oxytocin levels gradually decreased and oxytocin levels of 7-day-old infants were significantly lower than those in the umbilical artery, but higher than those in adults. In conclusion, it appears that maternal oxytocin levels may not be involved in triggering the onset of labor but may play a role in the maintenance and reinforcement of labor.

The effect of adrenocorticotropic hormone and dexamethasone, administered to the fetus in utero, upon maternal and fetal estrogens

Abstract Changes in maternal urinary estrogens and estrogen levels in maternal peripheral plasma and in umbilical plasma were studied after administration of adrenocorticotropic hormone (ACTH) or dexamethasone directly into the fetus or in the amniotic cavity during the mid-trimester of pregnancy. Estrogens in urine and umbilical plasma increased significantly following ACTH administration. After dexamethasone administration, urinary estrogens markedly decreased. These findings suggest that the estrogen production in pregnancy is regulated by fetal adrenal function.

A study on the development of sleep-wakefulness cycle in the human fetus

We observed fetal behavior by using three ultrasonic real-time scanners simultaneously in 30 normal pregnant women between 20 and 40 weeks of gestation and analyzed developmental changes in behavioral pattern focussing the attention on the characteristics of REM and non-REM sleep and wakeful state. The frequency of REM significantly increased with gestational age, and its occurrences formed a group in late pregnancy. REM and non-REM periods, which were defined as the phase with uninterrupted appearance of rapid eye movements and the phase without them over 3 min, respectively, became clearly distinguishable between 28 and 31 weeks of gestation. The correlation between the occurrence of rapid eye movements and breathing movements was high after 27 weeks. These results demonstrate the course of the development of sleep-wakefulness cycle in the human fetus.

Development of Artificial Placenta: Oxygen Metabolism of Isolated Goat Fetuses with Umbilical Arteriovenous Extracorporeal Membrane Oxygenation

To assess the oxygen utilization of extrauterine goat fetuses with arteriovenous extracorporeal membrane oxygenation via umbilical vessels, oxygen delivery (OD) and oxygen consumption (OC) were investigated in 19 long-term incubations (incubation periods 58-236 h). The OCs did not change (6.4 +/- 1.3 ml/min/kg, mean +/- SD, n = 227) when the ODs were more than 10 ml/min/kg, but were significantly suppressed when the ODs were less than 10 ml/min/kg. It was suggested that the oxygen metabolism of extrauterine goat fetuses is equivalent to that of fetuses in utero.

Steroid hormone levels in human fetal blood during delivery

Abstract Fetal blood samplings were made during labor according to Saling and Schneiders 13 techniques, and microdeterminations of plasma total estriol, dehydroepiandrosterone, and 16α-hydroxy-dehydroepiandrosterone were performed. All the steroids showed a tendency to increase during labor, and the difference in estriol levels was significant. The possible significance of the increase in estriol level and the fetal adrenal function during labor is discussed.

Computer-assisted analysis of fetal behavior in fetal abnormalities.

Fetal behavior was studied in 17 cases of fetal abnormalities including nonimmune hydrops fetalis and in 11 cases of intrauterine growth retardation (IUGR) in comparison to 30 healthy fetuses. Breathing movements, rapid eye movements and trunk movements were observed ultrasonically and analyzed using a computer-assisted system. The cases with central nervous system anomalies showed a markedly different behavioral pattern. In the fetal abnormalities without chromosomal anomalies, the cases without major behavioral disorders were cured by neonatal treatment. IUGR cases with decreased trunk, breathing and REM period were finally diagnosed as having fetal distress by fetal heart rate monitoring. The findings on fetal behavior hint at the possibility of diagnosing abnormalities in neural development as well as in well-being.

Plasma 11-deoxycortisol in normal and abnormal human pregnancy

11-Deoxycortisol was assayed in maternal and cord plasma. The concentrations in maternal plasma increased as pregnancy progressed and reached a peak at 39 weeks. The levels decreased very rapidly in the postpartum period. In cases of intrauterine fetal death and anencephalic fetuses, the values were apparently lower than normal. In women who had undergone bilateral adrenalectomy, the maternal plasma levels were almost normal. The maternal levels were high in cases of twin pregnancies. Therefore, it is assumed that the fetus or the fetoplacental unit is the source of the increased 11-deoxycortisol in maternal plasma during late pregnancy.