Amniotic fluid amylase concentration: a reliable predictor of fetal maturity?

The amylase concentration in the amniotic fluid (ACAF) was studied in 138 subjects in relation to duration of pregnancy, fetal weight, L/S ratios and neonatal occurrence of respiratory distress syndrome (RDS). ACAF was found to be significantly correlated with duration of pregnancy (p less than 0.001) and fetal weight (p less than 0.005). The number of false immature predictions, based on a critical value of ACAF of 200 U/l, was relatively high: 36% for the gestational age greater than or equal to 36 weeks, and 38% for fetal weight greater than 2,500 g. ACAF also showed a significant relationship with the L/S ratio (p less than 0.0001). ACAF less than 300 U/l correctly predicted all instances of L/S ratio less than 2.0; however, the rate of false low predictions was 60%. In only 22 out of 138 AF samples (16%) could the performance of an L/S ratio have been avoided on the basis of the ACAF. ACAF less than 300 U/l correctly predicted both cases of neonatal RDS in the study population; however, 1 of these fetuses had an ACAF of 260 U/l. There were four times as many false predictions of lung immaturity on the basis of ACAF less than 300 U/l as from the L/S less than 2.0.

Basal body temperature as a method of ovulation detection: comparison with ultrasonographical findings

In 47 cycles with hormonal evidence of ovulation, the detection and timing of ovulation by basal body temperature (BBT) and by ultrasonographical observation are compared. The ovulation detection rate by ultrasonographical method proves to be considerably higher than by BBT criteria. The timing of the day of ovulation is evaluated, assuming that the ultrasonographical event of follicle disappearance represents ovulation. BBT criteria nadir, coverline and the eye-balling method show a very poor frequency distribution. The result of the FDHP method is a nearly symmetrical distribution, however, with a considerable range. We conclude that ovulation detection and timing by BBT are not reliable.

Placental size during early pregnancy and fetal outcome: a preliminary report of a sequential ultrasonographic study

Placental growth during pregnancy was studied serially by ultrasonographic measurement of placental area in 50 primigravid women. Placental area at a menstrual age of 150 days was compared to infant birth weight. Small placental area at a menstrual age of 150 days was significantly related to low infant birth weight (< tenth percentile of birth weight for gestational age). A "warning limit" of placental area at midpregnancy was calculated. If placental area was equal to or smaller than this limit of 187 sq cm, six of nine patients (67%) compared to four of 41 subjects with larger placentas (p < 0.01) were delivered of a small-for-gestational age baby. Ultrasonographic placental area measurement in midpregnancy thus appears to be of prognostic value in identifying pregnancies at high risk for the subsequent occurrence of fetal growth.

Analysis of heart rate and beat-to-beat variability: Interval difference index

The relationshp between the RR interval length (RR) and the RR interval-to-interval differences (RR differences) was investigated. Data on heart rate were obtained from 11 newborn infants in well-defined behavioral states undergoing polygraphy. It was found that the RR differences were strongly dependent on the RR interval length in all behavioral states. The relationship between the RR differences (y) and the interval length (RR) could be described by the equation y = alpha (RR-320)1.5 for the interval length in the investigated range from 375 to 605 msec. On the basis of this relationship the interval difference index (ID index) was constructed for the quantification of beat-to-beat heart rate variability. The ID index showed good independence from the long-term irregularity index (LTI index). Other statistical parameters proposed for the quantification of beat-to-beat heart rate variability are discussed and compared with the ID index.

Ultrasonographic placental localization with respect to fetal position in utero

Ultrasonographic localization of the placental site was performed serially throughout pregnancy in 56 primigravidas with anteriorly located placentas. The placenta was found to be located on the right side of the uterus significantly more frequently than at any other site on the anterior uterine wall. Placental position was found to be related to the position of the fetus in utero. The role of placental location in determining the high incidence of the left occiput position at delivery is discussed.

Heart rate as an indicator of the behavioral state. Studies in the newborn infant and prospects for fetal heart rate monitoring

Term healthy newborn infants underwent polygraphy between days 4 and 6 of life. Behavioral states were determined according to Prechtl's criteria. The neonatal heart rate was analyzed for the various behavioral states, with the use of quantitative indices for long-term and short-term irregularity. The applied indices were, respectively, the long-term irregularity index (LTI index) and the interval difference index (ID index). During state 1 the R-R interval length was longer (p less than 0.01), the LTI index lower (p less than 0.01), and the ID index higher (p less then 0.02) than in the immediately preceding or following state 2. For nonconsecutive states 1 and 2 a maximum separation was obtained with the discriminant function 0.0159 RR - 0.065 LTI + 0.062 ID - 7.49. This discriminant function gave a total percentage of correct classification of states 1 and 2 epochs of 93%. The data are discussed with respect to the presence of cycling sleep states in the newborn infant as well as in the fetus. Prospects for fetal antepartum heart rate monitoring are considered.

The effect of diazepam administration during pregnancy or labor on the heart rate variability of the newborn infant

Maternal diazepam medication during labor reduces beat-to-beat variability of the fetal heart rate. In this study, the prolongation of the effect was examined in the newborn. The mother received diazepam: (A) during labor as a tranquilizer, (B) daily in low doses at the end of pregnancy, or (C) in high doses i.v. for (pre-)eclampsia. A control group had no analgesic or sedative during pregnancy or labor. The electrocardiogram (ECG) was recorded daily from each newborn during the first 6 days after birth. After preprocessing of the ECG, the median R-R interval, the long-term irregularity index (LTI index) and the interval difference index (ID index) were calculated. A cubic spline interpolation method was applied to compare the various groups with respect to these heart rate parameters. The median R-R interval showed no particular differences in trend for all groups. The LTI index was decreased in the first days after birth in the chronic diazepam (B), and in the diazepam infusion groups (C), but statistical significance was not reached. The ID index was significantly decreased in the first 1-2 days in the newborns of the acute and chronic diazepam group. In the diazepam infusion group, an even longer lasting effect was observed. Maternal diazepam medication affects the beat-to-beat variability in the newborn. The duration of the effect is dependent on dosage and route of administration.

Mechanisms of late decelerations in the fetal heart rate. A study with autonomic blocking agents in fetal lambs

Fetal heart rate decelerations resembling the late deceleration FHR pattern were produced in fetal sheep by periodic occlusion of the maternal common hypogastric artery for 30-60 sec. Transient fetal hypertension also occurred during the occlusions. Alpha-adrenergic blockade with phentolamine eliminated or markedly reduced the hypertensive response. FHR decelerations still occurred intermittently with some occlusions; however, their character was greatly altered. After parasympathetic blockade with atropine, the decelerations were replaced by periodic FHR accelerations during the occlusions. These accelerations were, in turn, eliminated by the beta-adrenergic blocking agent, propranolol. In the presence of combined parasympathetic, alpha- and beta-adrenergic blockade, the FHR remained essentially constant during the hypogastric artery occlusions in non-acidemic fetuses. FHR decelerations persisted after parasympathetic or total autonomic blockade when the fetuses were significantly hypoxic, as judged by depressed arterial blood pH and base excess values. Beat-to-beat variability of the baseline FHR persisted in the face of severe hypoxia and acidosis. These observations demonstrate that reflex mechanisms are involved importantly in the genesis of late deceleration FHR patterns in the acutely hypoxemic fetus, but that direct depression of myocardial rhythmicity becomes a factor as hypoxic acidosis develops.

Isolation of lysosomes from brain tissue. A separation method by means of alteration of mitochondrial and synaptosomal sedimentation properties

1. A crude mitochondrial-lysosomal preparation from brain tissue was layered on a sucrose gradient containing 20mm-succinate, 10mm-Tris and 1mm-disodium EDTA at pH7.4. The lysosomes were separated from the mitochondria and synaptosomes by means of a twosteps centrifugation procedure. In a first low-speed step (40min at 5300g at 15 degrees C) the sedimentation rate of mitochondria and mitochondria-containing synaptosomes was enlarged due to passage of these subcellular structures through the sucrose gradient with the above-mentioned chemicals (called ;chemical field'). That part of the gradient which contained the mitochondria and synaptosomes was removed and substituted by a gradient suitable for isopycnic isolation of lysosomes in a second centrifugation step. The achieved purification for bovine brain lysosomes was 5-8-fold, for rat brain lysosomes 7-10-fold, over the homogenate. 2. The enlargement of the sedimentation rate of mitochondria and synaptosomes was brought about by the presence of succinate, but also by one of the following salts in the chemical field: malonate, fumarate, pyruvate, phosphate and chloride. 3. Comparison of the chemical-field method with other methods for the isolation of lysosomes showed that (a) with the chemical-field method a 2-3-times higher purification of the rat and bovine brain lysosomal fraction can be achieved than with the procedure described by Koenig, Gaines, McDonald, Gray & Scott [(1964) J. Neurochem.11, 729-743], and that (b) similar purification results for rat liver lysosomes were obtained when the chemical-field method and the procedure described by van Dijk, Roholl, Reijngoud & Tager [(1976) FEBS Lett.62, 177-181] were compared.

Ultrasonographic diagnosis of intervillous thrombosis related to Rh isoimmunization

Greyscale ultrasonography of the placenta was performed in 54 primigravidae with placentas located on the anterior wall of the uterus, in a longitudinal study. During pregnancy single and multiple 'nodular increased transsonity' was seen echoscopically in the placenta. After birth these findings proved to be highly correlated to 'intervillous thrombosis'. The clinical value of these findings is discussed.

The lecithin/sphingomyelin ratio in Macaca arctoides

The amniotic fluid lecithin/sphingomyelin ratio (L/S ratio) of stumptail macaque monkeys (Macaca arctoides) was investigated by means of serial amniocenteses during the second half of pregnancy. Ten dated pregnancies were studied in 9 individual monkeys. The mean number of successful amniocenteses per pregnancy was 4. A rapid increase in the L/S ratio suggesting maturation of lung surfactant synthesis occurred as early as 130--140 days of pregnancy in some animals, and as late as 150--160 days in others. The earliest and latest times at which the L/S ratio first exceeded 2.0 were 135 and 164 days, respectively. These observations indicate that the L/S ratio of M. arctoides follows a course similar to that observed in human pregnancy, with a rise at 0.7--0.8 of term gestation. M. arctoides thus appears to be a useful model for the study of factors affecting fetal lung maturity, on the basis of the amniotic fluid L/S ratio. In particular, a rapid rise in L/S ratio before 130 days of pregnancy would be highly suggestive of accelerated maturation of pulmonary surfactant production.

Pressure in the hydrocephalic fetal head during the first stage of labor

Intraamniotic pressure was studied in the 30th week of amenorrhea in relationship with fetal intracranial pressure with open-tip catheters. The fetus had a severe hydrocephalus (echoscopy 16 cm) due to a teratologic malformation of the cerebrum. Clinically nonoperative treatment was indicated. Intracranial pressure (X) was invariably higher than intraamniotic pressure (Y) between contractions: Y = 2.04 + 0.54 X, and during contractions: Y = 5.30 + 0.55 X. There was no definite relationship between intrauterine and intracranial pressure, and the fetal tachogram. A definite relationship was established with the supine position of the patient and decelerations in the fetal tachogram. It is suggested that when fetal cardiac decelerations are seen during the first stage of labor it seems advisable to look for factors such as umbilical cord compression and decrease of materno-placental perfusion rather than fetal head compression.