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To determine if diabetes and preeclampsia are independent stimulators of erythropoietin, distinct from hypoxia, we measured umbilical cord plasma erythropoietin in 239 deliveries from 24 to 40 weeks of gestation. Mean plasma erythropoietin levels were not different between normal, diabetic, and preeclamptic women when all deliveries were analyzed. When infants with suspected intrauterine hypoxia were excluded, the mean erythropoietin level was considerably lower within all three groups but there was no difference among the groups. In suspected hypoxia, the mean fetal erythropoietin was elevated, but there was no difference between control, diabetic, or preeclamptic pregnancies. These results provide further support that hypoxia remains the only known stimulator of erythropoietin production in the fetus.

The effect of stimulus duration on the initial fetal heart rate (FHR) acceleration response was evaluated by assessing its amplitude and span following a single vibroacoustic stimulation with durations of 0 (sham), 1, 3, or 5 seconds. Statistically significant differences were observed in the mean amplitude and duration of acceleration in groups 3 and 5 when compared with groups 0 and 1 (P less than .05). In addition, groups 3 and 5 demonstrated significantly greater fetal reactivity than group 0 and a decrease in testing time over groups 0 and 1 (P less than .05). Our results suggest that the magnitude of the FHR acceleration response is dependent on the duration of the stimulus. Furthermore, a 3-second sound stimulus appears to be adequate for a shift to the fetal behavioral "awake" state.

Fetal movements were directly visualized with a real-time ultrasound unit, and they were recorded after the random intravenous administration of either glucose or saline solution to the mother. A significant increase in fetal activity was seen 1 hour after the administration of glucose.

The in vivo responsiveness of the ovine fetal and neonatal pituitary was investigated using acute and chronic preparations. Several studies were performed on six fetuses and six lambs from 112 days' gestation through 5 weeks after birth. Ten micrograms of gonadotropin-releasing hormone (GnRH) was injected intravenously into each fetus and lamb, and serial blood samples were collected from the fetus, ewe and lamb. The luteinizing hormone (LH) content of each sample was determined by species-specific radioimmunoassay. Both the fetus and the neonate showed a response to GnRH. A significant elevation of LH was found in all animals by 15 minutes. There was no response in the ewe when GnRH was injected into its fetus. Great variability in response was noted among various age groups and between animals, with the maximum individual LH response reaching 33.7 ng/ml. The maximum LH response of the neonate during the first week of life was significantly depressed (p < 0.05) as compared to that of the fetus and the older neonate.

Fetal head biparietal (BP) measurements by ultrasonic techniques and amniotic fluid lecithin-sphingomyelin (L/S) ratios were simultaneously determined (within 2 days) on 84 occasions in 72 women. Using the criteria for maturity of an L/S ratio of 2.0 or more or a BP measurement of 9.0 cm or more, there was agreement between these test results in 66.7% of the cases. The BP incorrectly predicted the L/S ratio 33.3% of the time, with a false positive rate of 27.3% and a false negative rate of 6.0%. If an L/S ratio of 1.5 were used as the critical determinant, the BP false positive rate remained high (9.5%). A high false negative error (21.4%) occurred if a BP value of 9.3 cm was used. These results suggest that ultrasonic BP measurements should not be used as the only criteria of fetal maturity in the management of high-risk pregnancies.

There were 254 cases studied in which two tests of fetal maturity were performed within 72 hours of each other. The two tests were an x-ray fetogram and an amniotic fluid L/S ratio determination. All fetograms were read by one author for the presence of distal femoral epiphysis (DFE). It was assumed that DFE permits estimation of fetal bone maturation and L/S ratio permits estimation of fetal lung maturity. The DFE results gave a 40% false-positive rate in predicting a mature L/S ratio (greater than 2.0) and a 38.7% false-negative rate. Of the 21 patients who delivered within 3 days of the performance of the two tests, all neonates did well when there were no visible DFE's but a mature L/S ratio. There is a significant lack of specificity and sensitivity of the fetogram DFE's in predicting a mature L/S ratio. Since infant lung maturation is a critical factor in predicting neonatal survival, these results suggest that the x-ray DFE is unacceptable as a single maturity test for use in a perinatal center managing complicated obstetric cases.

In order to evaluate the most reliable means of determining fetal maturity, six amniotic fluid components were analyzed from 99 women who were 22 to 40 weeks pregnant. The six parameters investigated were: amylase activity the lecithin to sphingomyelin (L/S) ratio, percentage of fat cells, and the concentrations of protein, creatinine, and bilrubin. In general, single components and combinations of two or three of the tests did not significantly enhance the predictive accuracy or reduce the error from that obtained with the L/S ratio used alone.

A prospective study of 268 normal pregnant women at term was undertaken in which serum concentrations of progesterone (P) and chorionic gonadotropin (HCG) were determined zero to four days before spontaneous labor. Neither HCG nor P changed significantly during these four days, although they were not measured serially in most women. There was no correlation between the HCG level and either the placental or infant weight, infant sex, or maternal serum progesterone concentration. The maternal serum P level was slightly but significantly correlated with the weight of the placenta (r equal to 0.24; p smaller than 0.001) but not with the fetal weight or infant sex. Thus, although the mass of trophoblastic tissue contributed in part to P concentration, other intracellular factors such as the cyclic adenosine monophosphate system are probably more important regulating mechanisms.

Fetal movements were measured by 37 pregnant women during a 10-minute period while they were lying on their left side at various times during the day with the highest rates in the evening. Preliminary assessments of fetal movement and serum hPL levels in pregnant women suggest that the two tests might complement each other in providing more information about the status of the placenta and fetus.