- Email: [email protected]
Reply to Monagle and Treffers et al.
872 Correspondence
We conclude that the evidence produced by the authors is insufficient to support their pretentious statements and that the system they are propagating implies a very high level of active intervention, which, in itself, could have undesirable consequences. P. E. Treffers D. van Alten M. Pel Department of Obstetrics and Gynecology University Hospital Wilhelmina Gasthuis Eerste H elmersstraat 104 1054 EG Amsterdam, The Netherlands REFERENCES 1. Smits, F.: De doeltreffendheid van het selectiesysteem bin-
nen de verloskundige wrg, Thesis, 1981, Nijmegen, The Netherlands. 2. Pel, M., and Treffers, P. E.: The reliability of the result of the umbilical cord pH, J. Perinat. Med. 11:1983. In press. 3. Lommen, E. J. P., and Meuwissen, J. H. J. M.: Icterus neonatorum, in ons land een verwaarloosde bedreiging? Ned. Tijdschr Geneeskd. 124:1685, 1980.
Reply to Monagle and Treffers et al. To the Editors: We did not condemn the system of obstetric care in The Netherlands. We advanced more or less conclusive evidence that this system is not as good as some of its supporters think it to be. Above all, we want scientific argumentation, not creed; we favor a discussion, not a debate. The issue raised on sampling and generalizability is a valid one. We investigated a sample of the Dutch obstetric population. Nine midwives agreed to collaborate, but the major contribution (82 of 104) was made by three midwives. Only as far as concerns these three midwives, the question of continuity need not be brought up, but it stands to reason that the other midwives did not prefer to contribute cases that, from a clinical point of view, would contribute to perinatal morbidity. The obstetric activity of the three midwives has been analyzed as thoroughly as possible, and a comparison with the Wormerveer group of van Alten 1 did not show any differences. From our personal knowledge of the skill and energy that the midwives put into their work, we can vouch that any other sample would convey perhaps equal, but certainly not better, results. The midwives who courageously collaborated in the study were convinced that the philosophy that underlies the Dutch system of obstetric care is correct. We strongly oppose any suggestion that the midwives, not the system, failed. The percentage of the cases they referred to the gynecologist because they judged them no longer physiologic was 49%, in contrast to the mere 30% referral in the Wormerveer study of van Alten. 1 We want to stress that our statement that the system
August I, 1983 Am.]. Obstet. Gynewl.
of obstetric care that prevails in The Netherlands is inadequate was not based on the prevalence of acidosis in the neonates delivered by the midwives compared with the prevalence of acidosis in the gynecologist group but on the outcome of the neurological examination. The outcome of our study was summarized as follows. "The occurrence of 10 neurologically nonoptimal infants in the midwife group is thought incompatible with the basic philosophy of the Dutch obstetric system, which is that midwives are able to select the normal pregnancies out of the group of women who present for obstetric care and can assist in maintaining the normal state in these selected cases in the course of delivery." We stated that the explanation for these findings presumably should not be sought predominantly in the inability of the midwives to detect a developing abnormality in the pregnant women who originally presented for obstetric care, but in the ability of the midwives to keep-with the tools available to them-all cases physiologic during delivery. Monagle takes issue with the definition of neonatal morbidity used in our study, which she deems to be arbitrary. Why the cutoff of six suboptimal items in defining a nonoptimal infant rather than zero, one, two, or three suboptimal items? The cutoff of six optimal items is rooted in the original article in which Prechtl described his system; it was used thereafter by de Jong2 • 3 and by Van den Berg-Helder. 4 The neonates examined by de Jong were followed up longitudinally for 4 years by Njiokiktjien and Kurver. 5 At the time of examination, all children were apparently normal and healthy. A significant difference was established between the infants who were originally diagnosed as optimal and those originally designated as nonoptimal. It should be stressed that-perhaps for the first time in history-these results evolved from a double-blind, prospective study. We abstained from looking for the number of nonoptimal items (zero, one, two, three, etc.) that would render a significant difference between groups, since this is not a sound procedure from a statistical point of view. We wanted primarily to guarantee that neonates would not be erroneously classified as neurologically nonoptimal. Therefore, the 99% upper confidence limit of zero for 42 was taken in order to obviate the possibility of including false positive results in the neonatal morbidity rate. Treffers and associates suggested that the absence of neurological abnormality in the gynecologist group was due to selection. One criterion for exclusion was hyperbilirubinemia necessitating phototherapy, and this criterion presumably favored the gynecologist group. A surplus of icteric neonates who did not receive phototherapy was kept in the midwife group, thereby accounting for the neonatal morbidity in that group. Even severe hyperbilirubinemia that indicates phototherapy (200 mg/100 ml on day 3 or 250 mgllOO ml later on) can, but does not necessarily, influence neuro-
Volume 146 Number 7
logical reactions and reflexes. In one of three neonates among the gynecologist group who were excluded, the influence of hyperbilirubinemia seemed to be obvious, but it would have been a subjective decision to exclude this case and to keep the other two in the study. Three other neonates with serum bilirubin values of 146 to 200 mg/ 100 ml were not excluded. The decision to apply phototherapy was not made by the investigators; moreover, among the 85 neonates delivered by the midwives, eight had some degree of jaundice. One of these eight was classified as neurological nonoptimal (score, 36). If we discard this case, the result is that, of 84 midwife deliveries, nine neurologically nonoptimal neonates were born (10.71 %: 95% confidence limits 5.02% and 19.37%), which still is not in accordance with the philosophy that underlies the Dutch system of obstetric care. Treffers and associates stated: "Evidently the selection of the gynecologist group was more strict than the selection of the midwife group." To support this statement, they quoted the wrong figures. Of the original gynecologist group, 40% were excluded; and of the original midwife group, 45% (and not merely 18%). Moreover, duration of amenorrhea and birth weight percentiles did not differ significantly between groups. Treffers and associates pointed out that in both groups the number of blood gas analyses did not concur with the number of neonates. This is correct. In the first drafts, mention was made that in one case in the gynecologist group the cord blood was coagulated, whereas in two cases in the midwife group only one sample of capillary blood was presented for add-base determination, thus rendering impossible a decision on whether arterial or venous blood was contained therein. Inadvertently, this information was lost in later revisions. We are indebted to Treffers for the opportunity to correct this omission. The delivery rooms in the hospital used by the gynecologists were adjacent to the delivery rooms in the hospital ambulatory unit used by the midwives for some of their patients. The laboratory housing the Corning 175 automatic pH and blood gas system were alongside the delivery rooms used by the midwives and the gynecologists. The acid-base measurements were performed by the same technicians immediately after arrival of the blood. Consequently, the time intervals between the sampling of the cord blood and the assay did not differ between the gynecologist group and the midwife ambulatory group. Since the acid-base values in the cord blood of the neonates delivered by the midwives in the hospital ambulatory unit did not differ from the values determined in the cord blood of the neonates delivered by the midwives at the patients' homes, we can safely assume that the influence of different transport and storage times was of minor importance. Moreover, the differences established between the gynecologist group and the midwife group as a whole were also found when the gynecologist group was compared with the midwife ambulatory group.
Correspondence 873
The relationship established between arterial cord blood pH and neurological optimality or nonoptimality consisted in the finding that a pH higher than 7.25 was hardly ever concomitant with nonoptimality, whereas optimality can be diagnosed with pH values higher and lower than 7.25. Identical findings were reported by Van den Berg-Helder. 4 In the Collaborative Study of Cerebral Palsy, Mental Retardation and other Neurological and Sensory Disorders of Infancy and Childhood,6 it was demonstrated that the Apgar score is an adequate indication of neonatal mortality but not of perinatal morbidity. Churchill and associates 7 established that the Apgar score of prematurely born spastic children did not differ from that of nonspastic premature infants. We ourselves 2 found a relationship between Apgar score and neurological score only for extremes. The data of Bowe and associates 8 relative to Apgar score and scalp blood values acquired some time in the course of delivery cannot be compared to our data obtained from arterial cord blood. The precision of the measurements of blood gas values was 0.005 for the pH and 0.08 kPa in the case of Pco 2 determination. The efforts of Pel to study the factors that influence the assay of the acid-base balance in cord blood suffer from misdirection, because the standardization of the time of clamping was neglected. The midwives agreed to clamp the cord as soon as possible after delivery. After placing one clamp on the cord, they could care for the infant, and after finishing, they aspirated cord blood. It is incorrect to state that "late clamping causes an increase in base deficit, while the influence on Pco 2 is less conspicuous." We 9• 10 established that late clamping (after 60 seconds) is concomitant with a decreased pH and an increased Pco 2 and base deficit. 1t was ascertained that the Pco2 in the midwife group did not differ from that in the gynecologist group, which remains in contrast with the differences in pH and base deficit that were established. Neonatal morbidity was observed only within the midwife group, in which group a relationship between acidosis and morbidity was established. Treffers and associates write that the base-deficit and Pco 2 values in the midwife group could depend on differences in clamping time and storage time, which is obviously nonsense. One can hardly surmise that the midwives were biased in such a way that they inadvertently or purposely delayed clamping and storage in the cases in which several days later the neonates proved to be neurologically nonoptimal. Six of the 10 neurologically nonoptimal and 31 of the 75 neurologically optimal neonates were delivered after an episiotomy had been performed. The length of the second stage affects the acid-base balance in a highly individual way. In one case, a short second stage will render a neonate acidotic, whereas in another case, a long stage will not. Shortening the second stage (episiotomy, forceps extraction, vacuum extraction) is indicated when scalp blood pH shows a definite decline. For that reason, we think that the duration of the
874 Correspondence
second stage and/or the use or nonuse of episiotomy is not an adequate base of comparison. Episiotomy was carried out in the gynecologist group to prevent severe acidosis and in the midwife group predominantly to prevent large perineal ruptures. Smits 11 established that in the Enschede area (2,236 newborn infants in 1974) 16 of the 51 perinatal deaths were not registered and, consequently, were not listed in the official perinatal death rate. M. Lievaart P. A. de]ong Department of Obstetrics and Gynecology Gemeente Ziekenhuis Bankastraat 57 Dordrecht, The Netherlands REFERENCES 1. Van Alten, D.: Site of delivery of nulliparae, Huisarts en Wetenschap 20:139, 1977. 2. Dejong, P. A.: The neurologic examination of the newborn according to Prechtl and Beintema as a yardstick for obstetric care, Thesis, 1975, Free University, Amsterdam, The Netherlands. 3. DeJong, P. A., and Stolte, L. A. M.: The validity of a neurological score based on Prechtl's concept of optimality, in Scientific Abstracts, Twenty-seventh Annual Meeting of the Society for Gynecologic Investigation, Denver, Colorado, March 19-22, 1980, p. 107.
August I, 1983 Am. J. Obstet. Gynecol.
4. Stolte, L. A. M., Van den Berg-Helder, A. F., Bouw, G. M., de Jong, P. A., van Kessel, H., Kurver, P. H. J., Njiokikyien, Ch.J., and Voorhorst, F.J.: The neurological status of the newborn infant as an endpoint of fetal well-being, in Symposium on Fetal Monitoring, Nijmegen, The Netherlands, 1980, University Press, pp. 151169. 5. Njiokik1Jien, Ch. ]., and Kurver, P. J.: Predictive value of neonatal neurological examination for cerebral functioning in infancy, Dev. Med. Child Neurol. 22:736, 1980. 6. Drage,]. S., Kennedy, C., and Schwarz, B. K.: The Apgar score as an index of neonatal mortality. A report from the Collaborative Study of Cerebral Palsy, Obstet. Gynecol. 24:222, 1964. 7. Churchill, J. A., Masland, R. L., Naylor, A. A.. and Ashworth, M. R.: The etiology of cerebral palsy in preterm infants, Dev. Med. Child Neurol. 16:143, 1974. 8. Bowe, E. T., Beard, R. W., Finster, M., Poppers, P. ]., Adamsons, K., and James, L. S.: Reliability of fetal blood sampling, AM.]. 0BSTET. GYNECOL. 107:279, 1970. 9. Lievaart, M., de Jong, P. A., and Stolte, L. A. M.: Timerelated changes in umbilical cord blood pH and gas tensions, in Scientific Abstracts, Twenty-eighth Annual Meeting of the Society for Gynecologic Investigation, St. Louis, Missouri, March 18-21, 1981, p. 154. 10. Lievaart, M., and de]ong, P. A.: Timeofclampingofthe umbilical cord after birth and acid-base equilibrium in cord blood, Obstet. Gynecol. Accepted for publication. 11. Smits, F.: The adequacy of the selection in obstetrical care, Thesis, 1981, Nijmegen, The Netherlands.
We conclude that the evidence produced by the authors is insufficient to support their pretentious statements and that the system they are propagating implies a very high level of active intervention, which, in itself, could have undesirable consequences. P. E. Treffers D. van Alten M. Pel Department of Obstetrics and Gynecology University Hospital Wilhelmina Gasthuis Eerste H elmersstraat 104 1054 EG Amsterdam, The Netherlands REFERENCES 1. Smits, F.: De doeltreffendheid van het selectiesysteem bin-
nen de verloskundige wrg, Thesis, 1981, Nijmegen, The Netherlands. 2. Pel, M., and Treffers, P. E.: The reliability of the result of the umbilical cord pH, J. Perinat. Med. 11:1983. In press. 3. Lommen, E. J. P., and Meuwissen, J. H. J. M.: Icterus neonatorum, in ons land een verwaarloosde bedreiging? Ned. Tijdschr Geneeskd. 124:1685, 1980.
Reply to Monagle and Treffers et al. To the Editors: We did not condemn the system of obstetric care in The Netherlands. We advanced more or less conclusive evidence that this system is not as good as some of its supporters think it to be. Above all, we want scientific argumentation, not creed; we favor a discussion, not a debate. The issue raised on sampling and generalizability is a valid one. We investigated a sample of the Dutch obstetric population. Nine midwives agreed to collaborate, but the major contribution (82 of 104) was made by three midwives. Only as far as concerns these three midwives, the question of continuity need not be brought up, but it stands to reason that the other midwives did not prefer to contribute cases that, from a clinical point of view, would contribute to perinatal morbidity. The obstetric activity of the three midwives has been analyzed as thoroughly as possible, and a comparison with the Wormerveer group of van Alten 1 did not show any differences. From our personal knowledge of the skill and energy that the midwives put into their work, we can vouch that any other sample would convey perhaps equal, but certainly not better, results. The midwives who courageously collaborated in the study were convinced that the philosophy that underlies the Dutch system of obstetric care is correct. We strongly oppose any suggestion that the midwives, not the system, failed. The percentage of the cases they referred to the gynecologist because they judged them no longer physiologic was 49%, in contrast to the mere 30% referral in the Wormerveer study of van Alten. 1 We want to stress that our statement that the system
August I, 1983 Am.]. Obstet. Gynewl.
of obstetric care that prevails in The Netherlands is inadequate was not based on the prevalence of acidosis in the neonates delivered by the midwives compared with the prevalence of acidosis in the gynecologist group but on the outcome of the neurological examination. The outcome of our study was summarized as follows. "The occurrence of 10 neurologically nonoptimal infants in the midwife group is thought incompatible with the basic philosophy of the Dutch obstetric system, which is that midwives are able to select the normal pregnancies out of the group of women who present for obstetric care and can assist in maintaining the normal state in these selected cases in the course of delivery." We stated that the explanation for these findings presumably should not be sought predominantly in the inability of the midwives to detect a developing abnormality in the pregnant women who originally presented for obstetric care, but in the ability of the midwives to keep-with the tools available to them-all cases physiologic during delivery. Monagle takes issue with the definition of neonatal morbidity used in our study, which she deems to be arbitrary. Why the cutoff of six suboptimal items in defining a nonoptimal infant rather than zero, one, two, or three suboptimal items? The cutoff of six optimal items is rooted in the original article in which Prechtl described his system; it was used thereafter by de Jong2 • 3 and by Van den Berg-Helder. 4 The neonates examined by de Jong were followed up longitudinally for 4 years by Njiokiktjien and Kurver. 5 At the time of examination, all children were apparently normal and healthy. A significant difference was established between the infants who were originally diagnosed as optimal and those originally designated as nonoptimal. It should be stressed that-perhaps for the first time in history-these results evolved from a double-blind, prospective study. We abstained from looking for the number of nonoptimal items (zero, one, two, three, etc.) that would render a significant difference between groups, since this is not a sound procedure from a statistical point of view. We wanted primarily to guarantee that neonates would not be erroneously classified as neurologically nonoptimal. Therefore, the 99% upper confidence limit of zero for 42 was taken in order to obviate the possibility of including false positive results in the neonatal morbidity rate. Treffers and associates suggested that the absence of neurological abnormality in the gynecologist group was due to selection. One criterion for exclusion was hyperbilirubinemia necessitating phototherapy, and this criterion presumably favored the gynecologist group. A surplus of icteric neonates who did not receive phototherapy was kept in the midwife group, thereby accounting for the neonatal morbidity in that group. Even severe hyperbilirubinemia that indicates phototherapy (200 mg/100 ml on day 3 or 250 mgllOO ml later on) can, but does not necessarily, influence neuro-
Volume 146 Number 7
logical reactions and reflexes. In one of three neonates among the gynecologist group who were excluded, the influence of hyperbilirubinemia seemed to be obvious, but it would have been a subjective decision to exclude this case and to keep the other two in the study. Three other neonates with serum bilirubin values of 146 to 200 mg/ 100 ml were not excluded. The decision to apply phototherapy was not made by the investigators; moreover, among the 85 neonates delivered by the midwives, eight had some degree of jaundice. One of these eight was classified as neurological nonoptimal (score, 36). If we discard this case, the result is that, of 84 midwife deliveries, nine neurologically nonoptimal neonates were born (10.71 %: 95% confidence limits 5.02% and 19.37%), which still is not in accordance with the philosophy that underlies the Dutch system of obstetric care. Treffers and associates stated: "Evidently the selection of the gynecologist group was more strict than the selection of the midwife group." To support this statement, they quoted the wrong figures. Of the original gynecologist group, 40% were excluded; and of the original midwife group, 45% (and not merely 18%). Moreover, duration of amenorrhea and birth weight percentiles did not differ significantly between groups. Treffers and associates pointed out that in both groups the number of blood gas analyses did not concur with the number of neonates. This is correct. In the first drafts, mention was made that in one case in the gynecologist group the cord blood was coagulated, whereas in two cases in the midwife group only one sample of capillary blood was presented for add-base determination, thus rendering impossible a decision on whether arterial or venous blood was contained therein. Inadvertently, this information was lost in later revisions. We are indebted to Treffers for the opportunity to correct this omission. The delivery rooms in the hospital used by the gynecologists were adjacent to the delivery rooms in the hospital ambulatory unit used by the midwives for some of their patients. The laboratory housing the Corning 175 automatic pH and blood gas system were alongside the delivery rooms used by the midwives and the gynecologists. The acid-base measurements were performed by the same technicians immediately after arrival of the blood. Consequently, the time intervals between the sampling of the cord blood and the assay did not differ between the gynecologist group and the midwife ambulatory group. Since the acid-base values in the cord blood of the neonates delivered by the midwives in the hospital ambulatory unit did not differ from the values determined in the cord blood of the neonates delivered by the midwives at the patients' homes, we can safely assume that the influence of different transport and storage times was of minor importance. Moreover, the differences established between the gynecologist group and the midwife group as a whole were also found when the gynecologist group was compared with the midwife ambulatory group.
Correspondence 873
The relationship established between arterial cord blood pH and neurological optimality or nonoptimality consisted in the finding that a pH higher than 7.25 was hardly ever concomitant with nonoptimality, whereas optimality can be diagnosed with pH values higher and lower than 7.25. Identical findings were reported by Van den Berg-Helder. 4 In the Collaborative Study of Cerebral Palsy, Mental Retardation and other Neurological and Sensory Disorders of Infancy and Childhood,6 it was demonstrated that the Apgar score is an adequate indication of neonatal mortality but not of perinatal morbidity. Churchill and associates 7 established that the Apgar score of prematurely born spastic children did not differ from that of nonspastic premature infants. We ourselves 2 found a relationship between Apgar score and neurological score only for extremes. The data of Bowe and associates 8 relative to Apgar score and scalp blood values acquired some time in the course of delivery cannot be compared to our data obtained from arterial cord blood. The precision of the measurements of blood gas values was 0.005 for the pH and 0.08 kPa in the case of Pco 2 determination. The efforts of Pel to study the factors that influence the assay of the acid-base balance in cord blood suffer from misdirection, because the standardization of the time of clamping was neglected. The midwives agreed to clamp the cord as soon as possible after delivery. After placing one clamp on the cord, they could care for the infant, and after finishing, they aspirated cord blood. It is incorrect to state that "late clamping causes an increase in base deficit, while the influence on Pco 2 is less conspicuous." We 9• 10 established that late clamping (after 60 seconds) is concomitant with a decreased pH and an increased Pco 2 and base deficit. 1t was ascertained that the Pco2 in the midwife group did not differ from that in the gynecologist group, which remains in contrast with the differences in pH and base deficit that were established. Neonatal morbidity was observed only within the midwife group, in which group a relationship between acidosis and morbidity was established. Treffers and associates write that the base-deficit and Pco 2 values in the midwife group could depend on differences in clamping time and storage time, which is obviously nonsense. One can hardly surmise that the midwives were biased in such a way that they inadvertently or purposely delayed clamping and storage in the cases in which several days later the neonates proved to be neurologically nonoptimal. Six of the 10 neurologically nonoptimal and 31 of the 75 neurologically optimal neonates were delivered after an episiotomy had been performed. The length of the second stage affects the acid-base balance in a highly individual way. In one case, a short second stage will render a neonate acidotic, whereas in another case, a long stage will not. Shortening the second stage (episiotomy, forceps extraction, vacuum extraction) is indicated when scalp blood pH shows a definite decline. For that reason, we think that the duration of the
874 Correspondence
second stage and/or the use or nonuse of episiotomy is not an adequate base of comparison. Episiotomy was carried out in the gynecologist group to prevent severe acidosis and in the midwife group predominantly to prevent large perineal ruptures. Smits 11 established that in the Enschede area (2,236 newborn infants in 1974) 16 of the 51 perinatal deaths were not registered and, consequently, were not listed in the official perinatal death rate. M. Lievaart P. A. de]ong Department of Obstetrics and Gynecology Gemeente Ziekenhuis Bankastraat 57 Dordrecht, The Netherlands REFERENCES 1. Van Alten, D.: Site of delivery of nulliparae, Huisarts en Wetenschap 20:139, 1977. 2. Dejong, P. A.: The neurologic examination of the newborn according to Prechtl and Beintema as a yardstick for obstetric care, Thesis, 1975, Free University, Amsterdam, The Netherlands. 3. DeJong, P. A., and Stolte, L. A. M.: The validity of a neurological score based on Prechtl's concept of optimality, in Scientific Abstracts, Twenty-seventh Annual Meeting of the Society for Gynecologic Investigation, Denver, Colorado, March 19-22, 1980, p. 107.
August I, 1983 Am. J. Obstet. Gynecol.
4. Stolte, L. A. M., Van den Berg-Helder, A. F., Bouw, G. M., de Jong, P. A., van Kessel, H., Kurver, P. H. J., Njiokikyien, Ch.J., and Voorhorst, F.J.: The neurological status of the newborn infant as an endpoint of fetal well-being, in Symposium on Fetal Monitoring, Nijmegen, The Netherlands, 1980, University Press, pp. 151169. 5. Njiokik1Jien, Ch. ]., and Kurver, P. J.: Predictive value of neonatal neurological examination for cerebral functioning in infancy, Dev. Med. Child Neurol. 22:736, 1980. 6. Drage,]. S., Kennedy, C., and Schwarz, B. K.: The Apgar score as an index of neonatal mortality. A report from the Collaborative Study of Cerebral Palsy, Obstet. Gynecol. 24:222, 1964. 7. Churchill, J. A., Masland, R. L., Naylor, A. A.. and Ashworth, M. R.: The etiology of cerebral palsy in preterm infants, Dev. Med. Child Neurol. 16:143, 1974. 8. Bowe, E. T., Beard, R. W., Finster, M., Poppers, P. ]., Adamsons, K., and James, L. S.: Reliability of fetal blood sampling, AM.]. 0BSTET. GYNECOL. 107:279, 1970. 9. Lievaart, M., de Jong, P. A., and Stolte, L. A. M.: Timerelated changes in umbilical cord blood pH and gas tensions, in Scientific Abstracts, Twenty-eighth Annual Meeting of the Society for Gynecologic Investigation, St. Louis, Missouri, March 18-21, 1981, p. 154. 10. Lievaart, M., and de]ong, P. A.: Timeofclampingofthe umbilical cord after birth and acid-base equilibrium in cord blood, Obstet. Gynecol. Accepted for publication. 11. Smits, F.: The adequacy of the selection in obstetrical care, Thesis, 1981, Nijmegen, The Netherlands.