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Twin pregnancy
Twin pregnancy A 12 year review from a private hospital service
D . W . SPAR L IN G, M . D . , F . R . C . 0 . G . , F . A . C . S . , F .A .C .0 . G . Montreal, Quebec, Canada
D u R I N G a recent review of perinatal mortality in the Montreal General Hospital, 1 we found that approximately two thirds of our perinatal deaths occurred in premature and immature babies. Further analysis of our data also revealed the fact that some 13 per cent of these deaths were found in twin pregnancies. This has prompted us to make a survey of all our multiple pregnancies from 1944, when the obstetrical service was first established in the Montreal General Hospital, until the end of 1962. It is realized that this is a selective group of patients, in that the prenatal care, delivery, postpartum period, and pediatric care were all under the personal supervision of qualified obstetrical and pediatric specialists. This would mean that comparisons with other reports where public patients were included would probably be invalid. During these 18)!2 years, therefore, 17,887 babies v1ere delivered in our hospital, of which 384 babies were twins. There were no triplets in the series. We have purposely included all babies where the combined weight of the two was at least 800 grams. This, naturally, results in higher mortality statistics, but we felt that a really comprehensive study of twin pregnancy would be incomplete if these smaller babies were not included.
Incidence. There was an over-all incidence of twins in the Montreal General Hospital during the period under review, of 1 in 92 pregnancies. This corresponds fairly closely with the figures quoted by Guttmacher11 for the United States of 1 in 90.3. Parity. Thirty-six per cent of our patients were primigravidas, and the remaining 64 per cent were multiparous. There did not appear to be any relationship between parity and perinatal mortality. Length of labor. The average length of labor in the primiparous patient was 10.6 hours, and in the multiparous patient it was 5.1 hours. It was interesting to note that in both cases the length of labor was less than that usually quoted for the patient with a single baby. We also found that the length of labor had no particular bearing on perinatal mortality. Zygosity. Unfortunately, our records were incomplete in this regard, and \Ve \vere unable to establish the zygosity of our twins. There were, however, 2 well-documented cases of monoamniotic twins in the series. One set lived, and the other will be noted elsewhere in this paper. Sex. Table I shows the relation of sex in the series. In all there were 190 male babies and 194 females. The first twin was a male 45.8 per cent of the time, and a female in the remaining 54.2 per cent of cases. It was interesting to note that 35 of the boy babies died as opposed to only 19 of the girls. The perinatal mortality rate, therefore, was 18.4 per cent for the
Presented by invitation at the Nineteenth Annual Meeting of the Society of Obstetricians and Gynaecologists of Canada, Toronto, Ontario, Canada, June 14-16, 1963.
349
350
l'rl"""'' I, 191i{
Sparling
,\nL
Table I. Sex of twins Mortality rate
%
No.
Sex
No.
32.8 33.9
63 65
30 18 66.7
33.3 100.0
6 4.7 54 14.0
128 35 29
I%
23.8 13.8 48 18.8
18.2 15.1 64 384
Table II. Perinatal mortality by combination
Vertex/vertex Vertex/breech Total vertex A
87 52
Breech/vertex Breech/breech Total breech A
20 20
Cesarean section Total over-all
62 38 139
25 12 73
37
15.2 11.5 13.3
40
21
5.0 25.0 12 15.0
13 192
6 100
5 19.3 54 14.0
50 50
2 10
Oh~L
&. ( ;ynt:'c.
was only 4. 7 per cent. This finding has also bt:>en reported by other writers."• '' If these figures were valid, it would appear that survival chances are greater if in twins a baby were a girl with a twin brother. Presentation and delivery. Table II lists the various presentations in our series. The first twin presented as a breech in 21 per cent of patients and as a vertex in 73 per cent. The remainder of the babies were delivered by cesarean section and the records did not often report the presentation. It would appear from this table that the perinatal mortality was about the same whether the vertex or the breech was delivered first. However, the breech group shows that there is a much higher mortality rate when both babies were delivered by breech. In Table III the deliveries are further broken down to show the incidence and mortality of each type of delivery. The highest mortality figures are those associated with spontaneous vertex deliveries, breech deliveries, and cesarean sections. Part of the reason for the high figures for spontaneous delivery is the large number of the immature babies that are in this group. This table points up again the relatively high mortality for the breech delivery. Cesarean section will be discussed later. The incidence of breech deliveries is considerably higher for the second baby. The apparently good mortality figures for version and extraction are not valid, of
males while it was only 9.7 per cent for the females. Twins of the same sex were found in 66.7 per cent of the patients, and mixed sexes in the remaining third. The perinatal rate for twins of the same sex was 18.8 per cent, whereas that for twins of different sexes
Male/male Female/female Same sex Male/female Female/male Different sexes Total babies
J,
Table III. Perinatal mortality by delivery ···-
Spontaneous Low forceps Mid-forceps Spontaneous breech Breech extraction Asst breech and ACHF Breech extraction and ACHF Version and extraction Cesarean section Totals
-~---
Twin A
--·-------
Twin B
Total
Perinatal mortality
Total
(%)
{%)
(%)
28.6 38.0 6.0 10.4 4.7 3.6 2.0
21.8 5.5
6.8
23.0
16.6 16.6 10.9 8.3 20.3 3.1 6.0 11.4 6.8
100.0
13.0
100.0
15.0 33.3
I
Total
Perinatal mortality
Total
(%)
(%)
21.8 15.6 4.7 37.5 12.9 16.6
I
Perinatal mortality
(%)
9.0 15.4
22.7 27.3 8.3 9.4 12.5 3.4 3.9 5.7 6.8
9.0 19.2
15.1
100.0
14.0
21.8 8.5 3.1 25.0 16.6 7.7
Volume 88 Number 3
course, due to the small number of cases recorded. Table IV summarizes the presentations with the mortality for each. Twin A shows a ratio of vertex to breech of 72.4 per cent to 20.8 per cent, whereas in Twin B the two figures tend to approximate each other, 44.3 per cent to 48.9 per cent of deliveries. On the other hand, the perinatal mortality figures are about the same in each case. The mortality in each case is, of course, many times that seen in the case of single babies. Weight. All writers have pointed out the fact that the greatest single factor influencing perinatal mortality in twin pregnancy is unquestionably the birth weight of the baby. This is amply illustrated in our own series, as is shown in Table V. In this study we have not used gestation time as an index of maturity due to its inaccuracy. On the other hand, a much more reliable method, we felt, was to use birth weight. We have, therefore, arbitrarily broken down our babies into three groups as follows: term, infants weighing 2,500 grams or over; premature, those weighing 1,000 to 2,499 grams; and immature, those weighing less than 1,000 grams. Table V shows the distribution of our babies using these criteria, and the perinatal mortality rates that were associated with each group. Futy-one per cent of all the babies in the series were considered term babies, and in this group there was no mortality. The "premature" babies consisted of 42.4 per cent of the entire group and the over-all mortality rate in these babies was 17.8 per cent. This mortality rate was 16.0 per cent for Twin A, and 19.5 per cent for Twin B. The remainder of the babies were classified as "immatures" and amounted to 6.8 per cent of the totaL The mortality rate here was 96.2 per cent. It would have been 100 per cent except fot the fact that one of the immatures, which weighed 1 pound 13 ounces at birth, survived and is now a normal healthy boy of 14 years. His twin, a boy weighing 2 pounds, died after a few hours of respiratory distress syndrome.
Twin pregnancy
351
Table IV. Perinatal mortality by presentation Twin A
Vertex Breech Section Total
Twin B
Total
Perinatal morTotal tality Total
Perinatal mortality Total
Perinatal mortality
(%)
(%)
(%)
(%)
(%)
(%)
72.4 11.5 20.8 15.0 6.8 23.0
44.3 48.9 6.8
15.3 14.9 15.4
58.3 34.9 6.8
12.9 14.9 19.2
100.0
15.1
100.0
14.0
100.0
13.0
Time interval. Table VI shows the various time intervals between the births of the first and second babies. Nearly 70 per cent of the second babies were delivered within 5 minutes of the first, and in these 132 babies the perinatal mortality rate was 16.6 per cent, which is only slightly higher than the 14.0 per cent for the entire group. Three quarters of the deaths were found in this time period. Most of the remainder were delivered in the next 10 minutes. According to the figures the highest mortality occurred in the 11 to 15 minute time period, but there were so few deliveries in this area as to make the rates invalid statistically. In only 9 cases was the time lag greater than 15 minutes. We are in agreement with others that undue haste as well as prolonged waiting are equally to be avoided in dealing with the second twin. Causes of perinatal mortality
We have attempted to assign the cause of death in accordance to Potter's five major classifications as shown in Table VII. In reviewing the cases we found that about 75 per cent of the deaths had postmortem examinations, but these were not always very helpful in establishing a cause of death, especially in the first two groupings. It is interesting to note from the table, that the same percentage pattern in causes of death is seen for Twin A as for the second twin. And, as has already been pointed out, the over-all mortality rate for each twin was about the same.
FdHUM)' I, 1964 Am.]. Obst. & Gynec.
352 Sparling
Table V. Perinatal mortality by weight Total (%)
Over 2,500 grams 2,500 grams J.,ess than 2,500 grams Totals
I
Total
Twin B
Twin A Mortality
Total
(%)
(%)
51.5 42.2 6.3
16.0 100.0
50.0 42.7 6.3
100.0
13.0
100.0
Immaturity was the most commonly listed cause of death in our series, accounting for 22 babies, or a rate of 41 per cent of the entire group. Five of these babies were deadborn, and the remainder died neonatally. Postmortem examinations in these babies were of little help in assigning any other cause of death than "immaturity." Possible contributing causes noted were premature rupture of mernberanes in one case, premature separation of the placenta with hydramnios in 5 other babies. Thirteen babies died neonatally of what we have termed abnormal pulmonary ventilation. Three sets of twin and seven single babies were in this group. At post mortem here we found that 3 of the babies had marked hyaline membrane disease, seven had atelectasis of severe degree, and three others had died from "respiratory distress syndrome." Placenta previa was associated with 2 of these deaths, toxemia with 1, prolapsed cord with 1, and premature mpture of the membranes with 2 others. Presumably, these associated conditions predisposed to premature onset of labor if not ultimately to the babies' deaths. Varying degrees of hypoxia or anoxia seemed to play an important role in 11 of the deaths, or 20 per cent of the entire group. Ten of these babies were deadborn and one died neonatally. Premature separation of the placenta was associated with 3 of the deaths, toxemia with 1, placental insufficiency with one, and tight coils of cord around the neck was considered the cause of death in 3 others. None of these last 3 was a result of version: they were all spontaneous vertex deliveries. Hydramnios appeared to play a part in two of these deaths.
j
Mortality
Total
(%)
(%)
19.5 92.8
50.8 42.4 6.8
15.1
100.0
I
Mortality (%)
17.8 96.2 14.0
--··--
Congenital anomalies incompatible with life were the cause of death in 7 babies, 2 of which were deadborn, the remaining dying neonatally. In each of 6 of these patients only 1 of the twins was affected, the other twin being normal. In the seventh patient the twins were thoracopagous, and both were deadborn. Hydramnios was not present in any of these congenital anomaly patients. The 1 remaining death in this series was due to erythroblastosis. The baby was deadborn, while its twin was born alive, Rh negative, and survived without treatment. Associated conditions. Approximately one half of all our twins were under 5 pounds, 8 ounces at birth, and were classified as premature or immature babies. One naturally wonders why prematurity is so common in twin pregnancies. Many reasons have been advanced, and Eastman2 has suggested that perhaps 50 per cent of premature births are without explanation. Multiple pregnancy is one of the leading predisposing causes of prematurity. One supposes that perhaps the uterus is not designed to hold such a large mass as term twin pregnancies in most cases. Associated conditions may play some part in the advent of premature labor. Pre-eclamptic toxemia was present in 12 of our patients, or 6.2 per cent. While this rate is not very high, it is, nevertheless, much higher than the general incidence of toxemia in our hospital service where it remains about 1 to 2 per cent of all admissions. One of the toxic patients with twins had eclampsia, but her twins were term and born alive and well. Only 4 of the toxic patients had premature labors. Premature separation of the placenta was noted in only 4 patients, but was associated
Volume88 NumberS
Twin pregnancy 353
Table VII. Causes of perinatal mortality
Table VI. Time interval
Time interval
I No.I
Under 5 minutes 132 6 to 10 minutes 38 11 to 15 minutes 13 16 minutes and over 9 Totals
192
% 69 20
7
IM~r-~Mortality rate taltty rate
(%)
22 2 4
16.6 10.0 57.0 11.1
29
15.1
4 100
with 5 immature deaths and 1 anoxia, out of 8 babies. Placenta previa was noted in 3 patients, 2 of whom had living term babies, and the other, although she had a cesarean section, had 2 premature babies which died with respiratory distress syndrome. Only one patient had diabetes. She was delivered by cesarean section of 2 premature babies both of which survived. Hydramnios was noted in 2 patients only, but in both of these cases both of the babies died. Cesarean section
Several authors have recently written about cesarean section in connection with twin pregnancy. 8 • 9• 10 The incidence of section in their series was 9.2 per cent, 3.6 per cent and 5.8 per cent, respectively. Our series is quite small, consisting of only 13 in all, or 6.8 per cent of the group. This is higher than our 3.9 per cent average of the period of time covered by this study. The indications for section were the usual ones, not because the patients had twins. Three were repeat sections, 3 were for placenta previa, and there was 1 each for diabetes, cardiac disease, cerebral disease, prolapsed cord, premature separation of the placenta, toxemia, and ovarian tumor. Five of the 26 babies were lost. Two were tiny immatures which died neonatally, in a patient sectioned for premature separation of the placenta and hydramnios. Two prematures died neonatally in a patient where the indication for section was placenta previa. And the one baby whose cord prolapsed,
%
Cause of death
Anoxia Abnormal pulmonary ventilation Congenital anomalies Erythroblastosis Totals
5
20
6
20 11
20
6 3
24 12
11
44
7 4 1 11
24 13 14 7 4 1 38 22
24 13 2 41
25 100
29 100 54 100
died with hyaline membrane disease and atelectasis. One of the patients who had a central placenta previa had an interesting x~ray picture wherein the 2 babies were lying in the transverse like "two sailors lying in their hammocks." These babies weighed 4 pounds 13 ounces and 5 pounds 11 ounces, respectively, at birth, and were discharged with their mother on her ninth postoperative day. Version and extraction
Twenty-two of our second babies were delivered by version and extraction. Some were turned from cephalic presentations, but most were changed from some degree of transverse lie. There were two perinatal deaths among these. One was a deadborn immature baby; the other died neonatally with respiratory distress syndrome. In spite of what appears to be fairly good results from the tables shown, we do not advocate version as a routine method for delivery of the second twin. Anesthesia
The type of anesthesia used in twin delivery has not been any different from that employed in any obstetrical patient on our service. It has varied with the years and the obstetrician in attendance. In 82 per cent of our cases inhalation anesthesia was used, varying from gas oxygen, to cyclopropane, and, more recently, fluothane. Spinal was used in only 23 patients and not recently. At the present time we are using more local infiltration, pudendal blocks, and when advisable, epidural anesthesia. A review of our
354 Sparling
cases shows no relationship at all between anesthesia used and perinatal mortality. Thoracopagous twins
We had during the time of this survey, one case of conjoined twins. At the time of delivery forceps were applied to the first head and it was delivered with some difficulty. However, when the shoulders did not readily follow, examination revealed the union anteriorly through the chest with the second twin. Forceps were then applied to the second head, and with some trouble it too was delivered, followed by the two bodies. The total weight of both twins was 10 pounds, and they were deadborn. Postmortem examination showed so much cross mixture of intestine and cardiovascular systems
REFERENCES
1. MacFarlane, K. T., and Sparling, D. W.: South. M. J. 55: 329, 1962. 2. Eastman, N. ].: Williams Obstetrics, ed. 12, New York, !961, Appleton-Century-Crofts, Inc., p. 678. 3. Guttmacher, A. F., and Kohl, S. G.: Obst. & Gynec. 12: 528, 1958. 4. Bulfin, M. J., and Lawler, P. E.: AM. J. 0BST. & GYNEC. 73: 37, 1957. 5. Spurway, J. H.: AM. J. 0BST. & GYNEC. 83: 1377, 1962. 6. Little, W. A., and Friedman, E. A.: Obst. & Gynec. Surv. 13: 611, 1958.
Discussion DR. A. W. ANDISON, Winnipeg, Canada. The conclusions drawn from this analysis of a series of twin pregnancies serve to emphasize, if that is necessary, the view to which all obstetricians of experience have long subscribed, namely, that the diagnosis of twins is not an occasion for the facetious or jocular remarks which it often provokes. While there are serious complications of multiple pregnancy which may befall the mother, such as postpartum hemorrhage, abruptio placentae, or eclampsia, these can be controlled or prevented by modern obstetric methods, and Dr. Sparling has rightly directed his attention to the outstanding problem of multiple pregnancy, that is, the extremely high perinatal death rate.
F('IHIJAJ)
1 Elbt
1\m . .I. Oh~t. & ( ;yrwc
as to have precluded surgical separation even had the twins been alive. Summary
In the past 18 years 192 sets of twins have been delivered on the obstetrical service of the Montreal General Hospital. This represents an incidence of 1 in 92 pregnancies. The gross perinatal mortality in the series was 14.0 per cent as compared with the hospital average for ali deliveries during the same time, of 0.26 per cent. There appeared to be a higher perinatal mortality in boy babies, and where twins were of the same sex. There was no significant difference in mortality rates between first and second babies.
7. Corston, J. M.: Obst. & Gynec. 10: 181, 1957. 8. Brody, S.: AM. J. 0BST. & GYNEC. 72: 19, 1956. 9. Posner, L. B., Lobell, N. J., and Posner, A. C.: Obst. & Gynec. 18: 355, I 961. 10. Guttmacher, A. F., and Mohl, S. G.: AM. J. OasT. & GYNEC. 83: 866, 1962. I I. Guttmacher, A. F.: Obst. & Gynec. 2: 22, 1953. 1414 Drummond Street Montreal, Quebec Canada
The fact that there were no deaths among infants who weighed over SY2 pounds reflects credit on those responsible for the management of these cases. But this means that the over-all perinatal mortality of 14 per cf'nt is actually nearly double this figure for infants whose birth weight was below the 57'2 pound limit. Even if one considers the group as a whole, the perinatal mortality rate is more or less comparable with that for cases of toxemia or placenta previa. To research into the first of these we devote untold timf' and money; on the other has been concrntrated a great deal of attention as regards diagnosis and management; and for both it is taken for granted that prolonged hospitalization and meticulous care are justified in order to im-
D . W . SPAR L IN G, M . D . , F . R . C . 0 . G . , F . A . C . S . , F .A .C .0 . G . Montreal, Quebec, Canada
D u R I N G a recent review of perinatal mortality in the Montreal General Hospital, 1 we found that approximately two thirds of our perinatal deaths occurred in premature and immature babies. Further analysis of our data also revealed the fact that some 13 per cent of these deaths were found in twin pregnancies. This has prompted us to make a survey of all our multiple pregnancies from 1944, when the obstetrical service was first established in the Montreal General Hospital, until the end of 1962. It is realized that this is a selective group of patients, in that the prenatal care, delivery, postpartum period, and pediatric care were all under the personal supervision of qualified obstetrical and pediatric specialists. This would mean that comparisons with other reports where public patients were included would probably be invalid. During these 18)!2 years, therefore, 17,887 babies v1ere delivered in our hospital, of which 384 babies were twins. There were no triplets in the series. We have purposely included all babies where the combined weight of the two was at least 800 grams. This, naturally, results in higher mortality statistics, but we felt that a really comprehensive study of twin pregnancy would be incomplete if these smaller babies were not included.
Incidence. There was an over-all incidence of twins in the Montreal General Hospital during the period under review, of 1 in 92 pregnancies. This corresponds fairly closely with the figures quoted by Guttmacher11 for the United States of 1 in 90.3. Parity. Thirty-six per cent of our patients were primigravidas, and the remaining 64 per cent were multiparous. There did not appear to be any relationship between parity and perinatal mortality. Length of labor. The average length of labor in the primiparous patient was 10.6 hours, and in the multiparous patient it was 5.1 hours. It was interesting to note that in both cases the length of labor was less than that usually quoted for the patient with a single baby. We also found that the length of labor had no particular bearing on perinatal mortality. Zygosity. Unfortunately, our records were incomplete in this regard, and \Ve \vere unable to establish the zygosity of our twins. There were, however, 2 well-documented cases of monoamniotic twins in the series. One set lived, and the other will be noted elsewhere in this paper. Sex. Table I shows the relation of sex in the series. In all there were 190 male babies and 194 females. The first twin was a male 45.8 per cent of the time, and a female in the remaining 54.2 per cent of cases. It was interesting to note that 35 of the boy babies died as opposed to only 19 of the girls. The perinatal mortality rate, therefore, was 18.4 per cent for the
Presented by invitation at the Nineteenth Annual Meeting of the Society of Obstetricians and Gynaecologists of Canada, Toronto, Ontario, Canada, June 14-16, 1963.
349
350
l'rl"""'' I, 191i{
Sparling
,\nL
Table I. Sex of twins Mortality rate
%
No.
Sex
No.
32.8 33.9
63 65
30 18 66.7
33.3 100.0
6 4.7 54 14.0
128 35 29
I%
23.8 13.8 48 18.8
18.2 15.1 64 384
Table II. Perinatal mortality by combination
Vertex/vertex Vertex/breech Total vertex A
87 52
Breech/vertex Breech/breech Total breech A
20 20
Cesarean section Total over-all
62 38 139
25 12 73
37
15.2 11.5 13.3
40
21
5.0 25.0 12 15.0
13 192
6 100
5 19.3 54 14.0
50 50
2 10
Oh~L
&. ( ;ynt:'c.
was only 4. 7 per cent. This finding has also bt:>en reported by other writers."• '' If these figures were valid, it would appear that survival chances are greater if in twins a baby were a girl with a twin brother. Presentation and delivery. Table II lists the various presentations in our series. The first twin presented as a breech in 21 per cent of patients and as a vertex in 73 per cent. The remainder of the babies were delivered by cesarean section and the records did not often report the presentation. It would appear from this table that the perinatal mortality was about the same whether the vertex or the breech was delivered first. However, the breech group shows that there is a much higher mortality rate when both babies were delivered by breech. In Table III the deliveries are further broken down to show the incidence and mortality of each type of delivery. The highest mortality figures are those associated with spontaneous vertex deliveries, breech deliveries, and cesarean sections. Part of the reason for the high figures for spontaneous delivery is the large number of the immature babies that are in this group. This table points up again the relatively high mortality for the breech delivery. Cesarean section will be discussed later. The incidence of breech deliveries is considerably higher for the second baby. The apparently good mortality figures for version and extraction are not valid, of
males while it was only 9.7 per cent for the females. Twins of the same sex were found in 66.7 per cent of the patients, and mixed sexes in the remaining third. The perinatal rate for twins of the same sex was 18.8 per cent, whereas that for twins of different sexes
Male/male Female/female Same sex Male/female Female/male Different sexes Total babies
J,
Table III. Perinatal mortality by delivery ···-
Spontaneous Low forceps Mid-forceps Spontaneous breech Breech extraction Asst breech and ACHF Breech extraction and ACHF Version and extraction Cesarean section Totals
-~---
Twin A
--·-------
Twin B
Total
Perinatal mortality
Total
(%)
{%)
(%)
28.6 38.0 6.0 10.4 4.7 3.6 2.0
21.8 5.5
6.8
23.0
16.6 16.6 10.9 8.3 20.3 3.1 6.0 11.4 6.8
100.0
13.0
100.0
15.0 33.3
I
Total
Perinatal mortality
Total
(%)
(%)
21.8 15.6 4.7 37.5 12.9 16.6
I
Perinatal mortality
(%)
9.0 15.4
22.7 27.3 8.3 9.4 12.5 3.4 3.9 5.7 6.8
9.0 19.2
15.1
100.0
14.0
21.8 8.5 3.1 25.0 16.6 7.7
Volume 88 Number 3
course, due to the small number of cases recorded. Table IV summarizes the presentations with the mortality for each. Twin A shows a ratio of vertex to breech of 72.4 per cent to 20.8 per cent, whereas in Twin B the two figures tend to approximate each other, 44.3 per cent to 48.9 per cent of deliveries. On the other hand, the perinatal mortality figures are about the same in each case. The mortality in each case is, of course, many times that seen in the case of single babies. Weight. All writers have pointed out the fact that the greatest single factor influencing perinatal mortality in twin pregnancy is unquestionably the birth weight of the baby. This is amply illustrated in our own series, as is shown in Table V. In this study we have not used gestation time as an index of maturity due to its inaccuracy. On the other hand, a much more reliable method, we felt, was to use birth weight. We have, therefore, arbitrarily broken down our babies into three groups as follows: term, infants weighing 2,500 grams or over; premature, those weighing 1,000 to 2,499 grams; and immature, those weighing less than 1,000 grams. Table V shows the distribution of our babies using these criteria, and the perinatal mortality rates that were associated with each group. Futy-one per cent of all the babies in the series were considered term babies, and in this group there was no mortality. The "premature" babies consisted of 42.4 per cent of the entire group and the over-all mortality rate in these babies was 17.8 per cent. This mortality rate was 16.0 per cent for Twin A, and 19.5 per cent for Twin B. The remainder of the babies were classified as "immatures" and amounted to 6.8 per cent of the totaL The mortality rate here was 96.2 per cent. It would have been 100 per cent except fot the fact that one of the immatures, which weighed 1 pound 13 ounces at birth, survived and is now a normal healthy boy of 14 years. His twin, a boy weighing 2 pounds, died after a few hours of respiratory distress syndrome.
Twin pregnancy
351
Table IV. Perinatal mortality by presentation Twin A
Vertex Breech Section Total
Twin B
Total
Perinatal morTotal tality Total
Perinatal mortality Total
Perinatal mortality
(%)
(%)
(%)
(%)
(%)
(%)
72.4 11.5 20.8 15.0 6.8 23.0
44.3 48.9 6.8
15.3 14.9 15.4
58.3 34.9 6.8
12.9 14.9 19.2
100.0
15.1
100.0
14.0
100.0
13.0
Time interval. Table VI shows the various time intervals between the births of the first and second babies. Nearly 70 per cent of the second babies were delivered within 5 minutes of the first, and in these 132 babies the perinatal mortality rate was 16.6 per cent, which is only slightly higher than the 14.0 per cent for the entire group. Three quarters of the deaths were found in this time period. Most of the remainder were delivered in the next 10 minutes. According to the figures the highest mortality occurred in the 11 to 15 minute time period, but there were so few deliveries in this area as to make the rates invalid statistically. In only 9 cases was the time lag greater than 15 minutes. We are in agreement with others that undue haste as well as prolonged waiting are equally to be avoided in dealing with the second twin. Causes of perinatal mortality
We have attempted to assign the cause of death in accordance to Potter's five major classifications as shown in Table VII. In reviewing the cases we found that about 75 per cent of the deaths had postmortem examinations, but these were not always very helpful in establishing a cause of death, especially in the first two groupings. It is interesting to note from the table, that the same percentage pattern in causes of death is seen for Twin A as for the second twin. And, as has already been pointed out, the over-all mortality rate for each twin was about the same.
FdHUM)' I, 1964 Am.]. Obst. & Gynec.
352 Sparling
Table V. Perinatal mortality by weight Total (%)
Over 2,500 grams 2,500 grams J.,ess than 2,500 grams Totals
I
Total
Twin B
Twin A Mortality
Total
(%)
(%)
51.5 42.2 6.3
16.0 100.0
50.0 42.7 6.3
100.0
13.0
100.0
Immaturity was the most commonly listed cause of death in our series, accounting for 22 babies, or a rate of 41 per cent of the entire group. Five of these babies were deadborn, and the remainder died neonatally. Postmortem examinations in these babies were of little help in assigning any other cause of death than "immaturity." Possible contributing causes noted were premature rupture of mernberanes in one case, premature separation of the placenta with hydramnios in 5 other babies. Thirteen babies died neonatally of what we have termed abnormal pulmonary ventilation. Three sets of twin and seven single babies were in this group. At post mortem here we found that 3 of the babies had marked hyaline membrane disease, seven had atelectasis of severe degree, and three others had died from "respiratory distress syndrome." Placenta previa was associated with 2 of these deaths, toxemia with 1, prolapsed cord with 1, and premature mpture of the membranes with 2 others. Presumably, these associated conditions predisposed to premature onset of labor if not ultimately to the babies' deaths. Varying degrees of hypoxia or anoxia seemed to play an important role in 11 of the deaths, or 20 per cent of the entire group. Ten of these babies were deadborn and one died neonatally. Premature separation of the placenta was associated with 3 of the deaths, toxemia with 1, placental insufficiency with one, and tight coils of cord around the neck was considered the cause of death in 3 others. None of these last 3 was a result of version: they were all spontaneous vertex deliveries. Hydramnios appeared to play a part in two of these deaths.
j
Mortality
Total
(%)
(%)
19.5 92.8
50.8 42.4 6.8
15.1
100.0
I
Mortality (%)
17.8 96.2 14.0
--··--
Congenital anomalies incompatible with life were the cause of death in 7 babies, 2 of which were deadborn, the remaining dying neonatally. In each of 6 of these patients only 1 of the twins was affected, the other twin being normal. In the seventh patient the twins were thoracopagous, and both were deadborn. Hydramnios was not present in any of these congenital anomaly patients. The 1 remaining death in this series was due to erythroblastosis. The baby was deadborn, while its twin was born alive, Rh negative, and survived without treatment. Associated conditions. Approximately one half of all our twins were under 5 pounds, 8 ounces at birth, and were classified as premature or immature babies. One naturally wonders why prematurity is so common in twin pregnancies. Many reasons have been advanced, and Eastman2 has suggested that perhaps 50 per cent of premature births are without explanation. Multiple pregnancy is one of the leading predisposing causes of prematurity. One supposes that perhaps the uterus is not designed to hold such a large mass as term twin pregnancies in most cases. Associated conditions may play some part in the advent of premature labor. Pre-eclamptic toxemia was present in 12 of our patients, or 6.2 per cent. While this rate is not very high, it is, nevertheless, much higher than the general incidence of toxemia in our hospital service where it remains about 1 to 2 per cent of all admissions. One of the toxic patients with twins had eclampsia, but her twins were term and born alive and well. Only 4 of the toxic patients had premature labors. Premature separation of the placenta was noted in only 4 patients, but was associated
Volume88 NumberS
Twin pregnancy 353
Table VII. Causes of perinatal mortality
Table VI. Time interval
Time interval
I No.I
Under 5 minutes 132 6 to 10 minutes 38 11 to 15 minutes 13 16 minutes and over 9 Totals
192
% 69 20
7
IM~r-~Mortality rate taltty rate
(%)
22 2 4
16.6 10.0 57.0 11.1
29
15.1
4 100
with 5 immature deaths and 1 anoxia, out of 8 babies. Placenta previa was noted in 3 patients, 2 of whom had living term babies, and the other, although she had a cesarean section, had 2 premature babies which died with respiratory distress syndrome. Only one patient had diabetes. She was delivered by cesarean section of 2 premature babies both of which survived. Hydramnios was noted in 2 patients only, but in both of these cases both of the babies died. Cesarean section
Several authors have recently written about cesarean section in connection with twin pregnancy. 8 • 9• 10 The incidence of section in their series was 9.2 per cent, 3.6 per cent and 5.8 per cent, respectively. Our series is quite small, consisting of only 13 in all, or 6.8 per cent of the group. This is higher than our 3.9 per cent average of the period of time covered by this study. The indications for section were the usual ones, not because the patients had twins. Three were repeat sections, 3 were for placenta previa, and there was 1 each for diabetes, cardiac disease, cerebral disease, prolapsed cord, premature separation of the placenta, toxemia, and ovarian tumor. Five of the 26 babies were lost. Two were tiny immatures which died neonatally, in a patient sectioned for premature separation of the placenta and hydramnios. Two prematures died neonatally in a patient where the indication for section was placenta previa. And the one baby whose cord prolapsed,
%
Cause of death
Anoxia Abnormal pulmonary ventilation Congenital anomalies Erythroblastosis Totals
5
20
6
20 11
20
6 3
24 12
11
44
7 4 1 11
24 13 14 7 4 1 38 22
24 13 2 41
25 100
29 100 54 100
died with hyaline membrane disease and atelectasis. One of the patients who had a central placenta previa had an interesting x~ray picture wherein the 2 babies were lying in the transverse like "two sailors lying in their hammocks." These babies weighed 4 pounds 13 ounces and 5 pounds 11 ounces, respectively, at birth, and were discharged with their mother on her ninth postoperative day. Version and extraction
Twenty-two of our second babies were delivered by version and extraction. Some were turned from cephalic presentations, but most were changed from some degree of transverse lie. There were two perinatal deaths among these. One was a deadborn immature baby; the other died neonatally with respiratory distress syndrome. In spite of what appears to be fairly good results from the tables shown, we do not advocate version as a routine method for delivery of the second twin. Anesthesia
The type of anesthesia used in twin delivery has not been any different from that employed in any obstetrical patient on our service. It has varied with the years and the obstetrician in attendance. In 82 per cent of our cases inhalation anesthesia was used, varying from gas oxygen, to cyclopropane, and, more recently, fluothane. Spinal was used in only 23 patients and not recently. At the present time we are using more local infiltration, pudendal blocks, and when advisable, epidural anesthesia. A review of our
354 Sparling
cases shows no relationship at all between anesthesia used and perinatal mortality. Thoracopagous twins
We had during the time of this survey, one case of conjoined twins. At the time of delivery forceps were applied to the first head and it was delivered with some difficulty. However, when the shoulders did not readily follow, examination revealed the union anteriorly through the chest with the second twin. Forceps were then applied to the second head, and with some trouble it too was delivered, followed by the two bodies. The total weight of both twins was 10 pounds, and they were deadborn. Postmortem examination showed so much cross mixture of intestine and cardiovascular systems
REFERENCES
1. MacFarlane, K. T., and Sparling, D. W.: South. M. J. 55: 329, 1962. 2. Eastman, N. ].: Williams Obstetrics, ed. 12, New York, !961, Appleton-Century-Crofts, Inc., p. 678. 3. Guttmacher, A. F., and Kohl, S. G.: Obst. & Gynec. 12: 528, 1958. 4. Bulfin, M. J., and Lawler, P. E.: AM. J. 0BST. & GYNEC. 73: 37, 1957. 5. Spurway, J. H.: AM. J. 0BST. & GYNEC. 83: 1377, 1962. 6. Little, W. A., and Friedman, E. A.: Obst. & Gynec. Surv. 13: 611, 1958.
Discussion DR. A. W. ANDISON, Winnipeg, Canada. The conclusions drawn from this analysis of a series of twin pregnancies serve to emphasize, if that is necessary, the view to which all obstetricians of experience have long subscribed, namely, that the diagnosis of twins is not an occasion for the facetious or jocular remarks which it often provokes. While there are serious complications of multiple pregnancy which may befall the mother, such as postpartum hemorrhage, abruptio placentae, or eclampsia, these can be controlled or prevented by modern obstetric methods, and Dr. Sparling has rightly directed his attention to the outstanding problem of multiple pregnancy, that is, the extremely high perinatal death rate.
F('IHIJAJ)
1 Elbt
1\m . .I. Oh~t. & ( ;yrwc
as to have precluded surgical separation even had the twins been alive. Summary
In the past 18 years 192 sets of twins have been delivered on the obstetrical service of the Montreal General Hospital. This represents an incidence of 1 in 92 pregnancies. The gross perinatal mortality in the series was 14.0 per cent as compared with the hospital average for ali deliveries during the same time, of 0.26 per cent. There appeared to be a higher perinatal mortality in boy babies, and where twins were of the same sex. There was no significant difference in mortality rates between first and second babies.
7. Corston, J. M.: Obst. & Gynec. 10: 181, 1957. 8. Brody, S.: AM. J. 0BST. & GYNEC. 72: 19, 1956. 9. Posner, L. B., Lobell, N. J., and Posner, A. C.: Obst. & Gynec. 18: 355, I 961. 10. Guttmacher, A. F., and Mohl, S. G.: AM. J. OasT. & GYNEC. 83: 866, 1962. I I. Guttmacher, A. F.: Obst. & Gynec. 2: 22, 1953. 1414 Drummond Street Montreal, Quebec Canada
The fact that there were no deaths among infants who weighed over SY2 pounds reflects credit on those responsible for the management of these cases. But this means that the over-all perinatal mortality of 14 per cf'nt is actually nearly double this figure for infants whose birth weight was below the 57'2 pound limit. Even if one considers the group as a whole, the perinatal mortality rate is more or less comparable with that for cases of toxemia or placenta previa. To research into the first of these we devote untold timf' and money; on the other has been concrntrated a great deal of attention as regards diagnosis and management; and for both it is taken for granted that prolonged hospitalization and meticulous care are justified in order to im-