The role of electronic fetal monitoring in labour.
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Biomedical subjects
Publications and source records attributed to I Ingemarsson.
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The impact of birth by caesarean section on perinatal mortality was estimated for 9368 low-birthweight twins (less than 2500 g) born in Sweden between 1973 and 1985, by using national data from the Medical Birth Registry, National Board of Health and Welfare, Stockholm. During this period the caesarean section rate increased from 7-10% to 45-50% while concomitantly a sharp decrease in the perinatal mortality rate occurred. A causal relation between the increased rate of abdominal delivery and the improved prognosis for low birthweight twins might be expected. However, analysis of the results failed to show any correlation between these two variables. Factors other than route of delivery seem to have a greater impact on fetal outcome.
The effects of isradipine (a new calcium antagonist of the dihydropyridine type) on maternal blood pressure and heart rate, fetal heart rate, and uterine activity in labour were measured. Uterine activity was recorded by an intrauterine microtip transducer catheter connected to a fetal monitor. Isradipine was given as a slow injection in doses of 0.5 mg (10 women), 1 mg (11 women), and 1.5 mg (6 women). A reduction of systolic (6-16%) and diastolic (19-22%) blood pressure was seen, and concomitantly there was an increase in maternal (29-34%) and fetal (3-10%) heart rates. Reduction in uterine activity was not dose-related (maximum reduction 17%). Side effects (headache, palpitations) were minor and well tolerated. One women in the high-dose group had a shortlasting episode of hypotension. The results suggest that isradipine given as a bolus dose decreases blood pressure in pregnant women with little effects on uterine activity and fetal heart rate.
We investigated the impact of a long interval between the birth of the first and the second twin on second twin perinatal mortality (PNM). National data in the Swedish Medical Birth Registry were used on 7533 second twins born in Sweden between 1973 and 1985. PNM as a function of the time interval between the births of the twins was studied in data from two time periods: during 1973-78 (n = 4008) and 1979-85 (n = 3525). During the first period, PNM was significantly higher at intervals of 30 min or more between the births of the twins than at shorter intervals (chi 2 = 11.1, p less than 0.001). When studied within broad birth weight classes, a significant trend was seen for twins weighing 1500-2499 g with an increasing interval (chi 2 = 8.1: p less than 0.01). A non-significant trend was also found for twins weighing less than 1500 g but none for twins weighing greater than or equal to 2500 g. During the second period, abdominal delivery of the second twin after vaginal delivery of the first twin was significantly more common than during the first period (2.0% vs 0.3%, chi 2 = 52.7, p less than 0.001). During the second period, the interdelivery interval had little impact on second twin PNM. The results of this study seem to indicate that with modern management of labor and delivery, as seen in Sweden since 1979, the interdelivery interval has little impact on second twin PNM.
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Intrapartum fetal heart rate patterns were investigated in pregnancies complicated by hypertension in a cohort study. The total number of live births was 2400 and the frequency of hypertension was 8.8%. The study group comprised 2023 normotensive and 200 hypertensive deliveries. Dates of all pregnancies were established at an ultrasound examination in week 17. Ominous intrapartum fetal heart rate patterns were significantly more common in hypertensive deliveries than in normotensive deliveries (20.5% versus 7.6%). The women with hypertension were compared with a group of control women matched for age, parity, induction of labor, and gestational week (20.5% versus 6.5%). In hypertensive women ominous fetal heart rate tracings were frequently associated with primiparity, induced labor, epidural block, delivery of a growth-retarded fetus, and beta 1-adrenergic receptor blockers. Ominous fetal heart rate patterns were less common in hypertensive women without these risk factors; still the significant differences in comparison with normotensive women remained. The hypertensive pregnancies accounted for no less than 21.0% of all ominous intrapartum fetal heart rate patterns, whereas 13% of all cases of ominous intrapartum fetal heart rate patterns could be attributed to the excess frequency in hypertensive pregnancies.
The immediate neonatal outcome by 2 different methods of assisted vaginal breech delivery was studied. In group A, spontaneous expulsion only up to the hip was allowed with one contraction and bearing down efforts; the rest of the baby was delivered with assistance with the next contraction and bearing down efforts. In group B the mother was allowed to expel the fetus up to the shoulders (with assistance) during one contraction and bearing down efforts, followed by assisted delivery of the head with the next uterine contraction and bearing down efforts. A decline in fetal blood pH (greater than 0.10) from the onset of delivery to cord arterial blood pH was more common in group B compared to group A; the difference being almost statistically significant (p = 0.54). Newborns with 1 min Apgar score less than 4 and with a need for assisted ventilation were significantly more common in group B (p less than 0.05). Exposure, stretching and compression of the umbilical cord for a longer time and possible separation of the placenta in group B may be the reason for such an outcome. Further studies are needed to establish the possible advantage of the method of delivery adapted in group A.
The value of quantifying active contraction area to guide oxytocin titration in augmentation of labour was investigated by a randomised trial. Sixty-eight nulliparae with slow progress of labour had oxytocin titrated to achieve preset "optimal" active contraction area or "optimal" frequency of contractions in a randomised manner. There was no difference in maternal characteristics of age and height, pre-augmentation period of observed labour or cervical dilatation at the onset of augmentation between the 2 groups. The maximum dose of oxytocin, post-augmentation period and the number of operative deliveries were similar. There was no difference in the mean birth weight of neonates, or in the number of neonates who had low Apgar score or acidotic cord arterial blood pH. Our results suggest that there may be no advantage in oxytocin titration to achieve preset "optimal" active contraction area compared with "optimal" frequency of uterine contractions in nulliparae with slow progress of labour.
Fetal vibroacoustic stimulation in fetuses with suspicious or ominous fetal heart rate traces in labour was followed by acid-base balance determination on fetal scalp blood within 30 min of the test. The mean fetal scalp blood pH values were significantly higher in fetuses that showed reactive responses with fetal heart rate acceleration compared with those who had no response or responded with a deceleration to the vibroacoustic stimulation (pH 7.30 and 7.22 respectively). However, acidotic scalp blood pH values (7.16 and 7.18) were found in two fetuses which had shown reactive responses both to vibroacoustic stimulation and pain stimuli with scalp blood sampling.
Uterine activity was measured in three groups of labouring women who previously had a caesarean section (CS): group A included women with a previous elective CS before labour or in the early latent phase of labour and no previous vaginal delivery; group B included women with a CS in the active phase of labour and no previous vaginal delivery; group C included women with a CS and a vaginal delivery either before or after the abdominal delivery. The active contraction area profiles in the three groups were compared with those of matched control groups of nulliparae and multiparae without a uterine scar. Group A had a uterine activity profile similar to that in control nulliparae and significantly higher than that in control multiparae. The uterine activity in group B was less than that in matched nulliparae but was similar to that in matched multiparae. Group C had significantly less uterine activity than matched nulliparae but a similar profile to that in the matched multiparae. Progress of labour into the active phase in the previous pregnancy reduces the uterine activity profile in subsequent labour. Women who had had a vaginal delivery either before or after the CS (group C) exhibited uterine activity profiles similar to multiparae, suggesting that an intact scar did not affect the uterine function.
Uterine activity was quantified in women with a previous caesarean scar and a slow progress of labour who needed oxytocin augmentation. Of the 63 women 49 (78%) progressed well (mean cervical dilatation rate of 1.5 cm/h) and were delivered vaginally. Fourteen women had slow progress of labour (0.3 cm/h) and were delivered by caesarean section despite adequate and similar augmented uterine activity to that in the women who were delivered vaginally. Those who were delivered by caesarean section had a significantly higher mean maximum dose of oxytocin and a longer period of augmentation. All caesarean sections were for cephalopelvic disproportion and the mean birthweight of babies born by caesarean section (3598 g) was significantly higher than that of babies born vaginally (3230 g). Satisfactory rate of cervical dilatation in the presence of optimal uterine activity is predictive of favourable outcome when oxytocin is used for dysfunctional labour after previous caesarean section.
In two cases of eclampsia with consumptive thrombocytopenia, the maximum increase in blood pressure and the lowest platelet count coincided with the maximum degree of neurologic and neuroradiologic abnormality. Computed tomograms showed decreased attenuation, and T2-weighted magnetic resonance images showed increased signal intensity focally in the cerebral cortex and the deep gray and white matter. Blood pressure, platelet count, clinical status, and roentgenograms normalized completely in both cases. Severe arterial hypertension and disseminated transitory microvascular occlusions presumably caused multiple small foci of brain edema that resolved without remaining detectable ischemic brain damage.
The effects of a new calcium antagonist, isradipine (PN 200-110) on postpartum uterine activity and the maternal cardiovascular system were investigated. Uterine activity was recorded by a microtip transducer catheter inserted transcervically within 45 min of normal vaginal delivery. 0.5 mg of isradipine was given as a bolus injection during 5 min to 7 women with spontaneous uterine activity and 1 mg was given during a 15-min period to another 8 women with oxytocin-stimulated uterine activity. Matched controls with similar pre-injection activity (+/- 5%) but not given the drug were selected for comparison. The effects of the drug in 3 women (given 1 mg of isradipine) were compared with those in matched controls and in women given 0.25 mg of terbutalin i.v. as a bolus injection. Isradipine had a marked inhibitory effect on both spontaneous and oxytocin-stimulated uterine activity. The inhibitory effect of 1 mg of isradipine seemed comparable to that of 0.25 mg of terbutalin. The inhibition occurred within 1-2 min after the injection and was sustained throughout the study period (2 h). A transient reduction of the systolic (mean maximum decrease 10-15%) and diastolic blood pressure (mean maximum decrease 15-20%) was seen, particularly during the injection period. Hypotension (systolic blood pressure less than 80 mmHg) was not recorded. A moderate increase in pulse rate (mean maximum increase 22-27%) was seen in all cases. The results show that isradipine given as a bolus injection can inhibit early postpartum uterine activity, with minimal side effects.
The rate of postoperative infections after cesarean section was studied in a prospective double-blind randomized study to compare cefuroxim with a placebo. Intravenous bolus injections were given at the beginning of, and 12h after the operation. Eighty patients received cefuroxim and 80 received placebo. Endometritis or wound infection, or both, was diagnosed in 2/80 (2.5%) patients receiving cefuroxim and in 23/80 (29%) patients receiving placebo. No side effects were demonstrated or reported by the patients. Thus, two bolus injections of 1.5 g of cefuroxim given perioperatively significantly reduced postoperative infectious morbidity after emergency cesarean section.
The aim of this study was to evaluate the efficacy of current methods in identifying fetuses with a weight greater than or equal to 5,700 g, and to study the perinatal mortality and morbidity in relation to the mode of delivery. Between 1973 and 1984, 110 newborns in Sweden had a birthweight greater than or equal to 5,700 g. These cases were identified using the National Medical Birth Registry, and from this data base, collecting antenatal, perinatal and infant data since 1973, a reference population was also selected. Tall, parous women with a high pre-pregnancy weight and an abnormal weight gain constituted a high-risk group, but the predictive potential of each of these variables was too low to allow identification of the individual case even in this extremely selected material. The obstetrician generally seemed to be unaware of the possibility of an extremely large fetus and only 7 (6.4%) women were delivered by an elective cesarean section, while 78 (70.9%) gave birth vaginally. Of 8 fetal deaths, 4 were related to shoulder dystocia, which occurred in almost 40% of all women who gave birth vaginally. Eleven newborns, all born vaginally, had a brachial plexus injury. The results of this study favor abdominal delivery for the extremely large fetus.
The interval from expected day of delivery to spontaneous onset of labor was correlated with parity and cervical score in 103 women with uncomplicated prolonged pregnancy (greater than 294 days). All women had a routine ultrasonic scan in weeks 16-18 for the purpose of dating. The mean (+/- SD) modified Bishop score on entry to the study was 4.15 +/- 2.0 for nulliparas and 4.90 +/- 2.1 for multiparas. The duration beyond 294 days to spontaneous onset of labor varied little (mean 3.5-4.5 days) for nulliparas with scores greater than 2 and for multiparas regardless of score. Nulliparous women with a poor score (less than 3) had spontaneous onset of labor and delivery within a mean of 9.8 days. Half of the multiparas (50.0%) and 43.9% of the nulliparas gave birth within 3 days. About 90% of all women gave birth within 7 days. All but three had a vaginal delivery; the instrumental vaginal delivery rate was 16.3%. The results suggest that in postterm women dated with a second-trimester ultrasonic scan, the cervical scores are in general more favorable than previously reported in series not dated with early scans. The postterm group is also much smaller, and the time interval from entry into the postterm period to spontaneous onset of labor is shorter.
Fetal heart rate reactions to the fetal acoustic stimulation test were investigated in 952 women in early labor. All had cephalic presentations (greater than 33 weeks of gestation) and were screened with a 15-minute fetal heart rate recording (admission test) before the sound stimulation was applied. Three different types of responses were observed: type I, an accelerative response; type II, a biphasic response with acceleration(s) followed by a deceleration; type III, no response or a prolonged deceleration (greater than 60 beats/min and greater than 60 seconds). A type I response was recorded in 98.0% of the women after a reactive admission test result, in 90.2% after an equivocal admission test result, and in 42.9% after an ominous admission test result. Fetal distress in labor occurred in these three groups in 2.0%, 22.2%, and 35.7% of cases, respectively. The risk for fetal distress was high after an ominous admission test and a type III response on the fetal acoustic stimulation test (75.0%). The fetal acoustic stimulation test might be of value in labor and give additional information about fetal well-being in patients previously screened by the admission test. Testing time can be shortened after an equivocal admission test.