Estimation of fetal shoulder width by measurement of the humerospinous distance by ultrasound.

The present study was undertaken to find a practical method for estimating the fetal shoulder width by ultrasound. Sixty pregnant women at term were included in the study. The distance between the lateral margin of the fetal cartilaginous caput humeri and the processus spinosus of the cervical vertebra C7 (humerospinous distance) was measured by ultrasound. The neonatal shoulder width was measured with a craniometer during the first postnatal day. Linear regression analysis was used to calculate the correlation between the humerospinous distance and the shoulder width, and a significant linear correlation (r = 0.612, p < 0.001) was shown. Although, in this small study, we could not show a relationship between humerospinous distance and dystocia, we feel a clinical study of humerospinous distance as a predictor of shoulder dystocia is indicated.

Emergency cesarean section: the effect of delay on umbilical arterial gas balance and Apgar scores.

BACKGROUND: We wanted to conduct a prospective study on the dynamics of emergency cesarean section (ECS) in terms of fetal survival and morbidity. METHODS: The study covered 101 cases of ECS in Helsinki City Hospital, in which the time of alarm, the starting time of the operation, the time of birth, the umbilical arterial gas values, and Apgar scores were known. This group consisted of 60 cases with the operating team in the hospital (group 1) and 41 cases with the team on call (group 2). Means of the parametric variables were compared by the analysis of variance using separate or pooled t-tests after Levene's test of variances. Difference between the rate of adverse outcome (dead or handicapped) in each group was calculated using chi-square test. RESULTS: In group 1, the time between the clinical decision and the time of delivery (mean +/- s.e.mean) was 13.5 +/- 0.7 min, in group 2, 23.6 +/- 0.9 min. The groups did not differ in terms of birthweight, placental weight, Apgar scores, and umbilical arterial gas values, except for pO2. The mean pO2 in group 1 was lower (1.9 +/- 0.1 kPa) than in group 2 (2.5 +/- 0.2 kPa). p = 0.0023. In group 2, one infant was handicapped by hypoxic ischemic encephalopathy and three fetuses had died in utero. The rate of survivors was significantly higher when the operating team was in hospital (p = 0.05). CONCLUSION: The risk of fetal loss is evident when the operating team is on call outside the hospital, at least if the alarm to operation interval exceeds 20 minutes. The present study suggests that 24-hour services of anesthesia and operating theater personnel are crucial for optimal management of emergent situations in the delivery room.

Significance of meconium staining of the amniotic fluid.

The study was conducted to determine the significance of meconium staining and more specifically its association with fetal heart rate patterns. Five hundred and one patients in labor were examined, 106 of whom had meconium stained amniotic fluid. A multivariate analysis of the data was performed by logistic regression analysis using meconium staining as the dependent variable. The determinants of meconium in the amniotic fluid were gestational age, base deficit, calcified placenta, late decelerations and placental weight. The following variables had no effect on the occurrence of meconium: maternal age, type of risk, parity, fetal sex, duration of labor, duration of the second stage of labor, entanglement of the umbilical cord, FHR variability, variable decelerations, oxytocin usage, type of anesthesia, maternal smoking and alcohol consumption habits. In conclusion, meconium in the amniotic fluid seems to be associated with placental rather than with umbilical insufficiency.

Maternal smoking and alcohol consumption as determinants of birth weight in an unselected study population.

A prospective study was conducted to determine the effects of maternal smoking and alcohol consumption during pregnancy on the birth weight of fetuses in an unselected study population. Several confounding factors were taken into account. The main factors associated with an increase of birth weight of both sexes were gestational age at birth and parity. Both maternal smoking and maternal alcohol consumption during pregnancy had the effect of decreasing the birth weight of female fetuses, whereas smoking, but not alcohol, had a decreasing effect on birth weight of male and female fetuses.

PIP: Many previous studies have confirmed that maternal smoking during pregnancy results in decreased infant birthweight, but few such studies have analyzed the possible confounding effect of maternal alcohol consumption. To clarify this issue, birthweight data were obtained on 752 male and 739 female infants delivered at Finland's University Central Hospital of Turku in 1984-86. Smoking was found to explain less than 2% of the variation in birthweight of both sexes and alcohol less than 1% of the variation among female infants; alcohol consumption did not account for any of the variation in birthweight among male infants. When the data for male and female infants were analyzed separately, increasing gestational age and parity were both found to contribute to increased birthweight, although gestational age explained considerably more of the birth weight variation of male infants (24%) than female infants (14%). When regression coefficients were employed, maternal smoking was associated with a reduction in the birthweight of male and female infants of 20 grams/cigarette smoked/day. On the other hand, alcohol consumption was associated with a reduction of 90 grams in the birthweight of females and had no effect on this variable in males. The interaction of maternal smoking and alcohol consumption was not significant for either male or female birthweights. The most significant finding of this study is that only female fetuses seem to suffer from maternal alcohol consumption during pregnancy.

Stress of delivery and plasma endorphins and catecholamines in the newborn infant.

Cord plasma levels of endorphins and catecholamines were correlated with the values of cord blood gas analysis and with hemodynamic parameters in 11 newborns (group A) delivered by elective cesarean section and in 18 newborns (group B) born spontaneously by vaginal route. All infants were in a good condition. No statistically significant differences were found in the mean cord plasma levels of adrenaline (A), noradrenaline (NA) and immunoreactive beta-endorphin (ir beta-E) between groups A and B. After spontaneous labor in group B a highly significant negative correlation was found between plasma NA level and pH and a positive correlation between NA and carbon dioxide tension in cord arterial blood and between NA and the short-term variability of the fetal heart rate before birth. Cord plasma A and ir beta-E did not show such correlations. These findings show that cord plasma level of NA is a sensitive indicator of minor stress during normal labor. After birth, during the first two hours of life, the mean plasma level of ir beta-E decreased in group B after vaginal delivery, but remained at a higher level in group A after elective cesarean section. This shows that the mode of delivery influences the neonatal endorphin secretion.

Intramuscular pethidine (meperidine) during labor associated with metabolic acidosis in the newborn.

Analyses of fetal heart rate (FHR) variability, visual evaluation of FHR decelerations, and respiratory gas analyses of the umbilical vein were performed in 27 labors, where one dose (50 or 75 mg) of intramuscular pethidine was used for pain relief, in 47 labors with one paracervical blockade (6 ml 0.5% marcaine) and in a control group of 135 labors without any pain relief. Umbilical vein pH, standard bicarbonate and base excess were lowest in the pethidine group and highest in the PCB group. The duration of labor was shortest in the control group, but there was no difference in the duration of labor of the two anesthesized groups. Intramuscular pethidine seems to associate with umbilical metabolic acidosis and PCB should be preferred to it, when an obstetrician is available.

Abdominal electrocardiography in intrapartum fetal heart rate monitoring.

Abdominal fetal electrocardiography (AFECG) as a means of intrapartum fetal heart rate (FHR) monitoring was studied in 700 consecutive labors in a small hospital. Sixty-eight pregnancies were excluded from the study because of the elective cesarean section or because labor was too short for electronic monitoring. AFECG succeeded (at least 30% of fetal heart intervals obtained) throughout labor in 99 of 632 monitored labors (16%). Ultrasound was needed in six cases (1%). The rest (527) were monitored first with the use of AFECG, and later with the use of direct FECG. The mean beat-to-beat variation of FHR (differential index) during last two hours of labor measured from AFECG signal was similar to that measured from AFECG and direct FECG. Hence the same reference values of the differential indices for both methods can be used. The mean long term variation (interval index) measured from AFECG was lower than that measured from abdominal and direct FECGs consecutively. Ultrasound is rarely needed during labor, and it should be avoided except in breech presentations, in association with low placentas and twins, if recording of AFECG fails.

Analysis of neonatal heart rate variability by a microprocessor-based on-line system.

The effects of different rejection logic limits on the results of analysis of neonatal heart rate variability from electrocardiograms by a microprocessor-based system were studied on fourteen infants after normal labor and on ten infants after elective cesarean section. In addition to the infant's movements and crying, two further main sources of error in the calculation of variability indices were detected: premature beats and problems in the shape of QRS complexes in a neonatal electrocardiogram. No noteworthy problem was observed in the calculation of the interval index (II), which describes the long term variability of heart rate. In the calculation of the differential indices (DI), which describe the short term component of heart rate, distorted QRS complexes created very high DIs when the rejection logic was ten beats per minute (bpm). When stricter rejection limits were used (five bpm), the DI values even in these cases fell within the normal range. The DI values calculated using a rejection limit of five bpm were always lower than those calculated using a rejection limit of ten bpm, but the reference values of neonatal II and DI after normal labor were similar to those presented previously using a rejection limit of ten bpm. In conclusion, the neonatal electrocardiogram appears to be a noisy signal, comparable with the abdominal fetal electrocardiogram, and strict rejection limits are useful in processing it for indices of variability.

Effects of smoking on fetal heart rate variability during gestational weeks 27 to 32.

PIP: 8 healthy mothers in weeks 27-32 of pregnancy gave informed consent for this study of the effects of smoking on fetal heart rate. Analyses of fetal heart rate (FHR) variability were performed at 1-minute intervals from an abdominal fetal electrocardiogram 10 minutes before, during, and 25 minutes after the mother smoked. Maternal heart rate (MHR) was recorded manually. An elevation of MHR and blood pressure occurred during smoking. Blood pressure had returned to initial levels either immediately (systolic) or within 10 minutes (diastolic); however, MHR was still elevated 25 minutes after smoking ceased. Baseline FHR increased 5 minutes after maternal smoking and returned to the normal level in 25 minutes. Correlation analysis shows negative correlations between the differential index and FHR, between differential index and pulse pressure (p.001), between differential index and systolic reading (p.01), and between variability indexes and MHR (p.001). There was also a positive correlation between FHR and MHR as well as between interval and differential indexes (p.001). The main finding of this study is that, at the onset of the 3rd trimester, the human fetus shows the decreasing effects of smoking on both interval and differential indexes, as does the term fetus (the differential index describes the short-term variability and the interval index describes the long-term variability of heart rate).^ieng

Fetal heart rate patterns and perinatal outcome of very-low-birthweight infants.

The obstetric records of 125 infants weighing 500-1250 g who were born in 1978 and 1979 at the Helsinki University Central Hospital were studied retrospectively to find out any associations between fetal heart rate (FHR) patterns and perinatal outcome. FHR recordings of 79 fetuses were available for study. Normal reactive patterns were observed in nine, nonreactive in 54, decelerations in 58, silent patterns in 45 and combined distress patterns in 36 fetuses. The interval from the first pathological sign to delivery was up to 27 days. Five fetuses in the monitored group died in utero, 26 infants died neonatally and two later. The risk of neonatal death after pathological FHR patterns was lower than after an FHR pattern without abnormality. Idiopathic respiratory distress syndrome (RDS) was diagnosed in 32 infants, of whom 16 died. Forty-seven fetuses (59%) of the monitored group were delivered abdominally and 32 vaginally. The risk of RDS was not significantly associated with FHR patterns and mode of delivery. We conclude that unlike term fetuses, low-birthweight fetuses seem to benefit from a period of intrauterine stress reflected in abnormal FHR patterns, if caesarean section is used liberally.

Reduced short-term variability of fetal heart rate in association with maternal hyperglycemia during pregnancy in insulin-dependent diabetic women.

The differential index, which describes the short-term component of fetal heart rate variability, and maternal blood glucose levels were measured 109 times in 19 insulin-dependent diabetic mothers in the second half of gestation. An abnormal differential index was observed more often with maternal hyperglycemia (11/45) than with normoglycemia (5/64). A significant negative linear correlation was found between the differential index and the blood glucose level of the mother.

Perinatal heart rate variability and circulatory adaptation in association with normal labor and after elective cesarean section.

Heart rate variability and basal hemodynamic parameters were studied in connection with 20 normal deliveries and after 16 elective cesarean sections. Eight of the cesarean sections were performed with the use of maternal barbiturate anesthesia and eight with the use of epidural blockade. The interval index describing the long-term variability and the differential index describing the short-term variability of the heart rate were measured continuously from 10-minute samples of a direct fetal electrocardiogram and a neonatal electrocardiogram of the infants by a microprocessor-based system. In association with normal labor, significant increases in both indices of variability were observed during the second stage of labor and during the first 2 hours of extrauterine life. After elective cesarean section both indices of neonatal heart rate variability remained significantly lower than those after normal labor. However, a significant increase was observed in the differential index of the infants delivered with the use of epidural blockade. During the neonatal period, simultaneous recordings of basal heart rate, systolic and diastolic blood pressures, and rectal and heel temperatures were made at 10-minute intervals. The basal neonatal heart rate was significantly higher in both cesarean section subgroups compared with that after normal labor. A significant decrease in basal neonatal heart rate during the second hour of life was observed after normal labor and after cesarean section with the use of epidural blockade. Systolic blood pressures in newborn infants delivered with the use of maternal epidural blockade were equal to those after normal labor, but higher than those after cesarean section with barbiturate anesthesia. Newborn infants after elective cesarean section had significantly lower diastolic blood pressures than infants delivered normally, but there was no difference in the diastolic blood pressures between the two cesarean section subgroups. The infants delivered vaginally had lower heel temperatures than those delivered abdominally. According to the present study, the neonatal circulatory adaptation after elective cesarean section is different from that after normal delivery; however, the neonatal hemodynamics after cesarean section with epidural blockade more closely resemble the situation after normal labor.

Short term variability of fetal heart rate during pregnancies complicated by hypertension.

The clinical significance of the differential index (DI), which describes the short term variability of fetal heart rate (FHR), in fetal surveillance was assessed in 202 hypertensive pregnancies. The analyses of FHR variability were made by a microprocessor-based on-line method using the abdominal fetal electrocardiogram as a triggering signal. The analysis was successful in 258 out of 323 trials (80%). Five perinatal deaths (2.5%) occurred in the whole series. Fetal distress developed in 47 out of 137 patients who had a successful FHR analysis within 1 week of delivery. The sensitivity of the antepartum DI in predicting fetal distress in labour was 46%, predictive value was 88% and specificity 97%. The risk of intrapartum fetal distress after a pathological DI was 4 times that after a normal DI (relative risk), which is highly significant.

Antepartum fetal heart rate variability and intervillous placental blood flow in association with smoking.

Intervillous placental blood flow and indices of fetal heart rate variability were measured from seven healthy pregnant women in the last trimester of pregnancy, once before and twice after smoking one cigarette. A blood flow reduction was observed in seven, a rise in five, and no change in two measurements. When intervillous placental blood flow decreased both indices of variability decreased (p less than 0.001), and when it increased the short-term component of fetal heart rate variability increased more significantly (p less than 0.001) than did the long-term component (p less than 0.01).

PIP: Intervillous placental blood flow and indices of fetal heart rate variability were measured from 7 healthy pregnant women in the last trimester of pregnancy, once before and twice after smoking 1 cigarette. Mean age was 27.3 years. The mothers were lying in 15 degrees left lateral recumbent position during the experiment. In 7 measurements a blood flow reduction equal to or more than 10% was seen. In 6 cases it was induced by smoking. Intervillous placental blood flow decreased from 93 +or- 11 (SD) to 74 +or- 10 ml/minute/100 ml intervillous blood volume. In 5 measurements an intervillous blood flow rise equal to over 10% was observed. In these cases intervillous placental blood flow increased from 79 +or- 23 to 98 +or- 23 ml. No correlation was observed between the absolute values of intervillous placental blood flow and the means of fetal heart rate variability indices. The main finding was that differential index and interval index correlated significantly with both decreasing and increasing intervillous placental blood flows. This study supports the hypothesis that the decrease of differential index is due to fetal hypoxia, possibly mediated by intervillous placental blood flow decrease, and that the decrease of interval index is due to a direct narcotic effect.

Midtrimester fetal heart rate variability and maternal hemodynamics in association with smoking.

Maternal heart rate (MHR), blood pressure (BP), the differential index (DI) describing the short-term component of fetal heart rate (FHR) variability, and the interval index (II) describing the long-term component were measured in eight subjects in the midtrimester before, during, and after the mothers smoked a standard cigarette. The analyses of FHR variability were performed by an "on-line" method with an abdominal fetal electrocardiogram used as a triggering signal and with a sample time of 1 minute. An increase of MHR, FHR, and BP with a concomitant decrease of II was observed. Unlike our findings regarding the third trimester, no significant change of DI was observed. A correlation analysis revealed fetomaternal hemodynamic relationships different from those in the third trimester: There was a negative correlation between DI and FHR (p less than 0.01) and between DI and MHR (p less than 0.01). There was a positive correlation between FHR and MHR (p less than 0.001). Unlike our findings regarding the third trimester, no correlation was found between DI and BP or between II and MHR. We suggest that the midtrimester fetus shows the narcotic effect (decrease of II) of one cigarette, as does the term fetus, but fails to show the hypoxic effect (decrease of DI), which has been observed in the term fetus.

Short term variability of fetal heart rate during insulin-dependent diabetic pregnancies.

The clinical significance of quantified short term variability of antepartal fetal heart rate (FHR) in prediction of fetal distress in labor was assessed in 120 insulin-dependent diabetic pregnancies. FHR was recorded by abdominal fetal electrocardiography (aFECG), from which the differential indices (DI) describing the short term variability of FHR were analyzed by a microprocessor-based on-line method. The analysis was successful in 308 of 350 trials (87%). In ten pregnancies, no acceptable a FECG was obtained. Fetal distress developed in 28 of the 110 pregnancies with successful FHR analysis. There were no intrauterine deaths in this series, but two newborn infants died (perinatal mortality 1.7%). Ninety-three pregnancies with FHR analyses within one week of delivery were included in the assessment of the test. DI predicted 2 of the 17 cases of fetal distress (sensitivity 67%). Twelve of the 18 cases with a pathological DI developed fetal distress (predictive value 71%). DIs were normal in 67 of the 73 pregnancies without fetal distress (specificity 92%). Risk of fetal distress after a pathological DI was 8.5 times that after normal DIs (relative risk), which is highly significant.