Biomedical subjects

C J Hobel

Publications and source records attributed to C J Hobel.

At least 19 recordsLinked to original sources

PubMed1992

Variations in the use of cesarean delivery for dystocia: lessons about the source of care.

Aggregate data show variations in the use of cesarean delivery according to the source of care, which suggests that rising cesarean rates are at least in part attributable to nonmedical factors. In the research presented here, the likelihood of cesarean delivery is examined for low-risk, primiparous women with physicians who practice in a single hospital but are from three practice organizations--a health maintenance organization (HMO), private practice, and a hospital clinic--while controlling for a wide spectrum of clinical factors. Maternal age was found to be a dominant factor in determining the decision for a cesarean delivery, independent of clinical risk and physicians' practice organization. Only among women in their optimal childbearing years (25 to 29 years) was having an HMO physician associated with a lower likelihood of cesarean delivery. The authors conclude that lowering the primary cesarean rate in the 1990's may require more reeducation and clinical policy formulation, with particular attention being paid to maternal age, and less reorganization of services than the aggregate data suggests.

Adult↗

PubMed1990

Uterine leiomyomas in pregnancy: a prospective study.

Uterine leiomyomas are associated with various complications during pregnancy. During a 2-year period, pregnant women with a history of leiomyomas were referred to our antenatal testing unit for ultrasound evaluation. Eighty-five patients were found to have single or multiple leiomyomas by ultrasound examination. The size (total leiomyoma volume), number, and location of the leiomyoma(s) were ascertained. Each woman with leiomyoma(s) was matched by age, race, and parity with one without leiomyomas. Both groups were followed throughout pregnancy, and outcomes were compared. Size, number, or location of the leiomyoma had no influence on outcome. Student t test indicated a significantly (P less than .01) lower mean gestational age at the time of delivery in women with leiomyomas.

Adult↗

PubMed1990

Perinatal outcome in triplet versus twin gestations.

The present study was conducted to determine whether triplet pregnancies are associated with a significantly worse perinatal outcome than twin pregnancies. Maternal and neonatal outcome was evaluated in 15 triplet and twin pregnancies that were matched for maternal age, race, type of medical insurance, delivery mode, parity, and history of previous preterm delivery. Preterm labor occurred significantly more often in triplet than in twin gestations (80 versus 40%), as did preterm delivery (87 versus 26.7%). Triplets had a significantly lower mean birth weight (1720 versus 2475 g) and gestational age at delivery (33 versus 36.6 weeks). In addition, 53.3% of triplet pregnancies but only 6.7% of twin pregnancies had one or more neonates with intrauterine growth retardation. Discordancy also occurred more frequently in triplets than in twins (66.7 versus 13.3%). The mean averaged neonatal hospital stay was significantly higher in triplets (29 versus 8.5 days), and triplets had a fivefold increased risk of requiring neonatal intensive care as compared with twins. However, there were no significant differences between the groups in maternal morbidity or major neonatal complications such as respiratory distress syndrome or intraventricular hemorrhage. We believe that these data will be useful in counseling patients with respect to the anticipated perinatal outcome of triplet pregnancies.

Adult↗

PubMed1990

The biophysical profile in labor.

To determine whether the biophysical profile would be a valuable intrapartum addition to fetal heart rate monitoring in predicting umbilical arterial acid-base status at delivery, 95 patients at term had serial studies during labor and umbilical artery blood gas analysis. There was no significant association between biophysical profile score and cord blood pH, nor was there a difference in scores between the acidemic and nonacidemic groups. Of the five components of the initial biophysical profile, only a nonreactive nonstress test (NST) was associated with both pH 7.20 or less (P = .019) and metabolic acidemia (P = .016). None of the individual variables of the final examination correlated with a pH of 7.20 or less. However, a nonreactive NST was associated with metabolic acidemia (P = .03), as was the presence of breathing (P = .03). Of the ten infants with pH 7.20 or less, eight had an initial and five had a final biophysical profile score of 8 or higher. Of the five whose pH was less than 7.15, four had an initial and three a final score of 8 or more. Finally, of the five with metabolic acidemia, four had an initial and two a final score of 8 or higher. Half of the acidemic fetuses had final biophysical profile scores of 8 or higher, suggesting that this score in labor is not reliable to rule out acidemia at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1989

Plasma atrial natriuretic peptide levels during the rat estrous cycle, pregnancy, and puerperium.

The rat has been used as a model for studying the changes that occur in maternal blood volume and renal function during pregnancy. The role, if any, that atrial natriuretic peptide plays in regulating these changes is unknown, and little information is available on atrial natriuretic peptide levels at different stages of gestation in the rat. In this study we measured plasma atrial natriuretic peptide levels by radioimmunoassay in the rat at each stage of the estrous cycle, during the last 2 weeks of pregnancy, and in the early postpartum period. Atrial natriuretic peptide levels did not change during the estrous cycle. Atrial natriuretic peptide levels were low on days 10 to 15 of gestation but rose to become significantly higher than nonpregnant levels on days 16 to 18. On day 21 shortly before delivery, levels were similar to nonpregnant values. Postpartum, atrial natriuretic peptide levels rose immediately and remained elevated for the next 48 hours. These findings suggest that factors other than blood volume may mediate plasma atrial natriuretic peptide levels during pregnancy and the postpartum period.

Animals↗

PubMed1989

Perinatal factors influencing atrial natriuretic peptide levels in umbilical arterial plasma at the time of delivery.

Little is known about atrial natriuretic peptide metabolism or secretion in the human fetus. The purpose of this study was to determine if both the placenta and umbilical vessels are possible sites of atrial natriuretic peptide metabolism and to evaluate the effects that labor, route of delivery, prolonged pregnancy, preeclampsia, and fetal distress have on umbilical arterial atrial natriuretic peptide levels. We found that plasma atrial natriuretic peptide levels in the umbilical artery are significantly greater than those in the vein (p less than 0.001). Umbilical arterial and umbilical venous atrial natriuretic peptide levels were higher in plasma samples collected immediately at delivery when compared with those obtained 10 minutes later (p less than 0.001). Umbilical arterial atrial natriuretic peptide levels were elevated in pregnancies complicated by preeclampsia and fetal distress (p less than 0.01). Labor, route of delivery, and prolonged pregnancy had no effect on umbilical arterial atrial natriuretic peptide levels. We propose that both the placenta and umbilical vessels contain atrial natriuretic peptide receptors that are involved in the clearance or metabolism of atrial natriuretic peptide. The increased umbilical arterial atrial natriuretic peptide levels present in preeclampsia and fetal distress may reflect an attempt by the fetus to regulate blood flow.

Atrial Natriuretic Factor↗

PubMed1989

Atrial natriuretic factor: the effects of pregnancy and a high-salt diet on atrial levels.

The chronic and relatively acute changes in blood volume that occur during pregnancy and post partum may be associated with alterations in the content of atrial natriuretic factor in the atria. We measured the concentration of atrial natriuretic factor in the right and left atria of virgin, pregnant, and postpartum Sprague-Dawley rats by radioimmunoassay as well as the concentration of atrial natriuretic factor in the atria and plasma of term pregnant rats on a high-salt diet. Neither right nor left atrial concentrations of atrial natriuretic factor were elevated during pregnancy in animals on a normal diet, but both were increased during the first 2 days after delivery. Term pregnant rats on a high-salt diet showed a small increase in atrial natriuretic factor levels in the left atria only, without any change in plasma atrial natriuretic factor levels. We conclude that relatively acute changes in fluid and electrolyte balance are more likely than chronic ones to be associated with alterations in atrial natriuretic factor concentrations in the atria.

Animals↗

PubMed1988

Ovine fetal lung fluid response to intravenous saline solution infusion: fetal atrial natriuretic factor effect.

The fetal lung, a significant source of in utero fluid production, has been postulated to serve a regulatory role in maintenance of fetal body fluid homeostasis. Whereas the fetus responds to intravascular saline solution infusions with increased urine output, the fetal lung fluid response to this stimulus is unclear. Tracheal fluid output was measured in four chronically catheterized ovine fetuses (mean gestation, 129 +/- 1 days) subjected to successive 40-minute intravenous 0.9% saline solution infusions at rates of 0.5 and 1 ml/min/per kilogram of body weight. Tracheal fluid output decreased significantly (1.7 +/- 0.1 to 1.1 +/- 0.1 ml/10 min, p less than 0.01) during the infusion and returned to basal levels during the recovery period. Lung fluid osmolality and electrolyte concentration did not change. Fetal plasma atrial natriuretic factor increased significantly in response to the saline solution infusion (364 +/- 90 to 790 +/- 286 pg/ml, p less than 0.05) and returned to basal levels during the recovery period. There was a significant inverse correlation between plasma atrial natriuretic factor levels and tracheal fluid output. These results suggest that increased fetal plasma atrial natriuretic factor decreases lung fluid production. Lung fluid does not appear to compensate for fetal body water excess. Rather, lung fluid production appears to promote intrauterine pulmonary growth and to facilitate the transition to the extrauterine environment.

Animals↗

PubMed1988

The efficacy of starting postterm antenatal testing at 41 weeks as compared with 42 weeks of gestational age.

Postterm antenatal fetal surveillance has traditionally begun at 42 completed weeks of gestation. However, recent data have shown that a significant percentage of cases of perinatal asphyxia occurs between 40 and 42 weeks of gestation. We compared the perinatal outcome of fetuses with antenatal surveillance beginning at 41 weeks to those starting at 42 weeks of gestation. The study groups consisted of 908 patients who began antenatal testing at 41 weeks and 352 who began testing at 42 weeks. Antenatal testing consisted of twice-weekly amniotic fluid assessments and nonstress tests (including evaluation for late and variable decelerations). Between 41 and 42 weeks, the group whose testing started at 41 weeks had an overall incidence of intrapartum fetal distress of 2.7%, no stillbirths, and no infants with major neonatal morbidity. Patients without antenatal testing who delivered between 41 to 42 weeks did not have a significantly increased incidence of fetal distress (3.3%; p = 0.07). However, this group had a significantly increased incidence of adverse outcomes (p less than 0.05), including three stillbirths and seven cases of major neonatal morbidity. Beyond 42 weeks, the group whose testing started at 41 weeks had a 2.3% overall incidence of fetal distress. This was significantly less (p less than 0.01) than the group whose testing started at 42 weeks (5.6%). Neither of the groups had any stillbirths or infants with major neonatal morbidity. These findings suggest that starting antenatal testing at 41 weeks of gestation may result in decreased postterm perinatal mortality and morbidity as well as a decreased incidence of intrapartum fetal distress.

Female↗

PubMed1988

Atrial natriuretic peptide in the sheep.

To study atrial natriuretic peptide (ANP) physiology in the chronically catheterized pregnant sheep model we developed a heterologous radioimmunoassay for ovine ANP using an antiserum raised against 1-28 human ANP. This antiserum (Tor I) is specific for the aminoterminus of the human ANP molecule and shows little cross reaction with any carboxyterminus ANP fragments. Ovine ANP immunoreactivity was characterized using this antiserum and a commercially available carboxyterminus ANP antiserum obtained from Peninsula Laboratories. Each antiserum detected 2 peaks of immunoreactivity in ovine atrial extracts chromatographed on a Biogel P-10 column. The minor peak migrated at a position close to 125I-human ANP whereas the major peak represented a larger molecular weight species of ANP. Examination of gel filtration eluates of ovine plasma extracts showed one immunoreactive ANP peak using the Tor I assay system and 2 peaks with the Peninsula Laboratories assay. Plasma immunoreactive ANP levels were determined in 9 sheep using both radioimmunoassay systems. Mean (+/- SEM) levels were similar using the Peninsula Laboratories and the Tor I assay systems (57 +/- 8 pg/ml versus 43 +/- 4 pg/ml, P greater than 0.05). Using the Tor I antiserum, fetal plasma immunoreactive ANP levels were found to be significantly higher than maternal levels (188 +/- 17 versus 48 +/- 8 pg/ml, P less than 0.01) whereas pregnant and nonpregnant adult sheep had similar plasma immunoreactive ANP levels (48 +/- 8 versus 43 +/- 4 pg/ml, P greater than 0.05). Disappearance curves of synthetic human ANP from the plasma of maternal and fetal sheep were assessed using both immunoassay systems and found to be similar.

Animals↗

PubMed1987

Early third-trimester ultrasound screening in gestational diabetes to determine the risk of macrosomia and labor dystocia at term.

The purpose of this study was to determine whether an early third-trimester fetal abdominal circumference measurement can be used in patients with gestational diabetes to predict the presence or absence of macrosomia and labor dystocia at term. The predictive accuracy of a 30- to 33-week abdominal circumference measurement was tested, using the ninetieth percentile as the discriminant point. The study consisted of 201 patients with gestational diabetes who maintained weekly fasting glucose levels less than 100 mg/dl and 2-hour postprandial glucose levels less than 120 mg/dl with dietary management alone. The predictive accuracy of a 30- to 33-week fetal abdominal circumference measurement was 96.4% for ruling out macrosomia and 56.3% for predicting macrosomia. Patients with fetal abdominal circumference measurements greater than the ninetieth percentile at 30 to 33 weeks had a significantly increased incidence of cesarean section for failure to progress, shoulder dystocia, and birth trauma, whereas patients with abdominal circumference measurements less than or equal to the ninetieth percentile were at no greater risk than the general population. These results suggest that patients with non-insulin-dependent gestational diabetes with fetal abdominal circumference measurements less than or equal to the ninetieth percentile at 30 to 33 weeks are not at increased risk for macrosomia, cesarean section, or birth trauma at term, as long as their weekly glucose testing remains within normal limits. Efforts to decrease the incidence of macrosomia and its attendant risks should focus on those gestational diabetic patients whose fetal abdominal circumference greater than the ninetieth percentile at 30 to 33 weeks.

Adult↗

PubMed1987

Antepartum predictors of fetal distress in postterm pregnancy.

The purpose of this study was to determine the efficacy of combining nonstress testing with ultrasound assessment of amniotic fluid volume for the antenatal evaluation of the postterm fetus. Postterm patients (884) were managed with amniotic fluid assessments and nonstress tests (including evaluation for variable and late decelerations) twice a week. There were no perinatal deaths or major neonatal morbidity. However, the antenatal testing sensitivity, specificity, negative, or positive predictive values were not improved by combining the two tests. Individually, amniotic fluid assessment was just as accurate a predictor of fetal well-being and was a significantly more sensitive test than the nonstress test. In addition, antenatal predictors of fetal distress and intrapartum signs of fetal distress were almost exclusively those reflective of umbilical cord compromise. These findings stress the importance of antenatal screening for signs of umbilical cord compromise as an early indication of potential fetal compromise. Although the results also suggest that amniotic fluid assessment is superior to the nonstress test, they do not conclusively support the use of amniotic fluid assessment as the sole parameter for postterm antenatal surveillance.

Amniotic Fluid↗

PubMed1987

The role of antepartum testing in the management of postterm pregnancies with heavy meconium in early labor.

The documented association between heavy meconium in early labor and increased perinatal morbidity and mortality has alerted physicians to the presence of a potential high-risk fetal condition and to the possible need for immediate fetal blood pH determination. The purpose of this study was to determine whether antepartum fetal assessment can predict whether a postterm fetus with heavy meconium in early labor is at low or high risk for an adverse perinatal outcome. Eight hundred thirty-nine postterm patients were followed with antepartum testing, consisting of twice-weekly fetal heart rate (FHR) testing and ultrasonic amniotic fluid volume estimation. Overall, patients with heavy meconium in early labor had a significantly greater frequency of fetal distress. However, when women with heavy meconium in early labor were separated according to their antepartum testing results, those with normal results were found to have no greater risk for fetal distress or perinatal morbidity than women with normal testing and subsequently clear amniotic fluid. These findings suggest that postterm patients with heavy meconium in early labor and normal antepartum testing can be managed in labor in the same manner as low-risk patients without meconium.

Amniotic Fluid↗

PubMed1987

Fetal gender effects on maternal serum prolactin levels.

Circulating maternal prolactin (PRL) levels have been reported to be higher in term pregnancies yielding male infants. The mechanism for this gender difference is unknown, but we theorized that it was mediated through the fetal adrenal cortex. To test this theory we measured circulating PRL and estriol (E3) concentrations with radioimmunoassay in 37 pregnant women at 34 and 36 weeks' gestation. We then separated the groups by newborn gender. Maternal serum PRL levels were significantly higher in the women bearing male fetuses. There was no significant difference by gender in E3 concentrations, and there was no PRL surge corresponding to the E3 surge at 34-36 weeks' gestational age. There was no correlation between E3 and PRL levels. Transmission of the fetal gender effect on maternal PRL does not appear to be mediated through the fetal adrenal as measured by the fetoplacental production of E3. The effect probably is mediated by the fetal gonad.

Adrenal Cortex↗

PubMed1986

Blunted response of maternal ovine placental lactogen levels to arginine stimulation after single umbilical artery ligation in pregnant sheep.

Ovine placental lactogen levels in the maternal circulation are significantly reduced after single umbilical artery ligation in pregnant sheep. We report the ovine placental lactogen response to high-dose amino acid stimulation in four ewes with fetuses that underwent single umbilical artery ligation and six control ewes with fetuses that underwent sham operation. After maternal infusion with 50 gm of arginine in 350 ml of distilled water, mean ovine placental lactogen levels in ewes with fetuses that underwent single umbilical artery ligation increased by 170%, while mean levels in control ewes increased by 294%. Maternal infusions with hypertonic saline solution of osmolality and volume equal to those of the arginine solutions failed to increase maternal ovine placental lactogen levels. Fetal well-being, both during and after the maternal arginine infusions, was confirmed by unchanged fetal arterial blood gases and catecholamines. The ovine placental lactogen levels in the fetal circulation were not altered by maternal arginine infusion. These data suggest that the correlation between maternal ovine placental lactogen levels and functioning placental mass may be enhanced by arginine stimulation. The possible use of this provocation of placental lactogen levels as a test of placental function in clinical practice is discussed.

Animals↗

PubMed1986

A simplified risk-scoring system for prematurity.

Prematurity, the major cause of perinatal morbidity and mortality, results from a multifactorial interaction of medical, historic, and psychosocial conditions. Although the literature contains several reports of prematurity risk-scoring systems, the relative importance of specific risk factors may depend on the population studied. This report represents the first prematurity risk-scoring system designed specifically for a predominantly Hispanic population in the United States. Retrospective analysis of 8240 births occurring at Harbor/UCLA Medical Center from July, 1979 to December, 1982 identified maternal prenatal risk factors that were found to be statistically related to prematurity. A linear logistic regression model was then employed to derive a composite risk score. Using the logistic risk scores, we developed a simplified model for identifying women at risk for preterm birth. The methodology and analyses provide a system for the development of population-specific risk scoring.

Analysis of Variance↗

PubMed1986

Prenatal and perinatal factors associated with brain disorders.

In April 1985, a report entitled "Prenatal and Perinatal Factors Associated with Brain Disorders" was published by the National Institutes of Child Health and Human Development and the National Institute of Neurological and Communicative Disorders and Stroke. A panel of ten individuals completed the report documenting the knowledge and the complexities of what is known with respect to brain damage that may develop before birth or in the neonatal period. It is clear that all stages of fetal and neonatal development influence normal outcome. Although intrapartal period events may explain a significant portion of cerebral palsy, the illness is often linked with confounding factors such as low birth weight and asphyxia. Pure epilepsy or pure mental retardation is rarely associated with intrapartal events. In general, the pathologic lesions seen in the brain may reflect many different fetal insults. The same clinical event such as asphyxia may result in varied intracranial diseases, which effects may depend on when the clinical events occurred.

Brain↗

PubMed1984

Fetal catecholamine release with preterm delivery.

Neurosympathetic system activity at birth was studied by measuring umbilical arterial plasma catecholamine concentrations in 36 preterm fetuses. Umbilical arterial catecholamine concentrations were correlated with blood gas status, mode of delivery, fetal sex, and fetal heart rate patterns. Significant correlations were observed for plasma norepinephrine and epinephrine versus fetal pH and PO2 and for plasma dopamine versus pH but not PO2. These catecholamine relationships to acidosis and hypoxia were similar to those of our previously published data for term fetuses. Norepinephrine and dopamine concentrations were similar in both preterm and term fetuses; however, epinephrine levels were significantly greater in preterm fetuses than in term fetuses. Increased concentrations of norepinephrine, epinephrine, and dopamine were observed in association with abnormal fetal heart rate patterns. There was no significant effect of fetal sex on the catecholamine secretory response. Similar cord catecholamine concentrations were observed following vaginal and cesarean section delivery, the latter with and without labor. These results indicate that the preterm fetus, like the term fetus, responds to stress at delivery with a graded catecholamine release. The observation of greater epinephrine concentrations in preterm fetuses than in term fetuses may reflect increased secretion or decreased clearance of epinephrine.

Dopamine↗